(CNN)Search teams have been looking for the wreckage of Malaysia Airlines Flight 370 for nearly two years, and thus far, boats dragging high-tech detection equipment across the Indian Ocean and teams searching from the skies have had little success.

This week, hopes of finding out what happened to the plane were renewed when an American tourist found a piece of plane debris off the coast of Mozambique. The debris appeared to be from a Boeing 777, like the missing MH370 airliner, according to a U.S. official. But Cmdr. Joao Abreu, the chief executive of the Mozambique Civil Aviation Authority, told CNN’s David McKenzie that the piece of debris might belong to a “medium-sized plane” and not a 777.
Authorities from Australia and Malaysia have urged caution before jumping to conclusions, and the debris is on its way to Australia for further examination.

5 photos: MH370 debris discovered on Reunion Island

5 photos: MH370 debris discovered on Reunion Island
Debris discovered on the island of Reunion, a French territory in the Indian Ocean, was confirmed to be from Malaysia Airlines Flight 370, Malaysian Prime Minister Najib Razak said August 5. The plane disappeared in March 2014 with 239 people on board.

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5 photos: MH370 debris discovered on Reunion Island
French police officers carry the plane debris on July 29. Experts say the metallic object may be a piece of a moving wing surface, known as a flaperon, from a Boeing 777.

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5 photos: MH370 debris discovered on Reunion Island
Police officers inspect debris on July 29.

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5 photos: MH370 debris discovered on Reunion Island
Another piece of debris resembles remnants of a suitcase.

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5 photos: MH370 debris discovered on Reunion Island
Police carry debris on July 29.

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Until now, the closest searchers have come to finding the whereabouts of the missing plane came on July 29 when airplane debris was found on the shores of a French island in the Indian Ocean. It was wreckage from a Boeing 777 — the same type of aircraft as MH370. In September, French investigators confirmed it: The wing part found on Reunion Island was from the plane that disappeared with 239 people on board in March 2014, en route from Kuala Lumpur, Malaysia, to Beijing.
The find created hope that the rest of the plane would soon be located, but months passed with no major developments.

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As search crews return to the seas after a break, here’s a look at some of things items they’ve found in the past two years:

Old Ironsides In December 2015, a team found a 200-year-old shipwreck while searching for Flight 370. “An anomalous sonar contact was identified in the course of the underwater search, with analysis suggesting the object was likely to be man-made, probably a shipwreck,” said the Joint Agency Coordination Centre, the Australian Transport Safety Bureau agency directing the search. In January, searchers sent out a ship called Havila Harmony to take a picture using the sonar on board an autonomous underwater vehicle, the agency said. They showed the image to experts at the Shipwreck Galleries of the Western Australian Museum, who said the wreckage is probably a ship made of steel or iron from the early 19th century. As surprising as the find may seem, it wasn’t the first shipwreck the searchers found in the search zone. Search vessel Fugro Equator’s deep tow system “detected a cluster of small sonar contacts” of potential interest near the so-called 7th arc. Pictures revealed startlingly clear images of a previously uncharted wreck, also most likely from the 19th century, according to Australian authorities. An anchor, as well as parts of a destroyed hull, were clearly seen in the photos of the wreck 3,900 meters (12,795 feet) deep.

Some of the shipwreck’s shinier debris initially piqued searchers’ interest as possibly being pieces of MH370. But the plane still eluded them.

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Seen today, gone tomorrow On March 24, 2014, the same day Malaysian Prime Minister Najib Razak broke the news to anguished families of MH370 passengers that new data suggested the flight ended in the southern Indian Ocean, searchers thought they had a clue as to just where to find it. Australian officials said they had spotted two objects in the southern Indian Ocean that could be related to the flight. One object was “a gray or green circular object,” and the other was “an orange rectangular object,” the Australian Maritime Safety Authority said at the time. Mary Schiavo, a CNN aviation analyst and former inspector general for the U.S. Department of Transportation, said gray/green is the color of the inside of the aircraft and that metal and other things in the aircraft are of gray/green color, everything from the metal in the fuselage and pieces of the mechanical parts, while orange and bright yellow are the color of the emergency escape slides and life rafts inside the plane. But the Australian naval ship HMAS Success didn’t turn up the objects when it searched and a U.S. surveillance plane sent to follow up was unable to find the objects, which had been the latest in a series of sightings, including “suspicious objects” reported by a Chinese military plane. Ten aircraft — from Australia, China, the United States and Japan — searched the area. Days before, on March 22, a civilian aircraft reported seeing a wooden pallet as well as strapping belts, Australian authorities said. While wooden pallets were among the items on Flight 370, such pallets are common in the ocean shipping industry, so they may be unrelated.

A Royal New Zealand Air Force P-3 Orion was sent to the area, but only reported seeing bunches of seaweed, according to Australian authorities.

41 photos: The search for MH370
In late February 2016, American tourist Blaine Gibson found a piece of plane debris off Mozambique, a discovery that renewed hope of solving the mystery of missing Malaysia Airlines Flight 370. The piece measures 35 inches by 22 inches. A U.S. official said it was likely the wreckage came from a Boeing 777, like MH370. Others were more skeptical.

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41 photos: The search for MH370
On July 29, police carry a piece of debris on Reunion Island, a French territory in the Indian Ocean. A week later, authorities confirmed that the debris was from MH370, which disappeared on March 8, 2014.

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41 photos: The search for MH370
Relatives of the flight’s passengers console each other outside the Malaysia Airlines office in Subang, Malaysia, on February 12, 2015. Protesters had demanded that the airline withdraw the statement that all 239 people aboard the plane were dead.

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41 photos: The search for MH370
A police officer watches a couple cry outside the airline’s office building in Beijing after officials refused to meet with them on June 11, 2014. The couple’s son was on the plane.

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41 photos: The search for MH370
Members of the media scramble to speak with Azharuddin Abdul Rahman, director general of Malaysia’s Civil Aviation Department, at a hotel in Kuala Lumpur, Malaysia, on May 27, 2014. Data from communications between satellites and the missing flight was released the day before, more than two months after relatives of passengers said they requested it be made public.

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41 photos: The search for MH370
Operators aboard the Australian ship Ocean Shield move Bluefin-21, the U.S. Navy’s autonomous underwater vehicle, into position to search for the jet on April 14, 2014.

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41 photos: The search for MH370
A member of the Royal New Zealand Air Force looks out of a window while searching for debris off the coast of western Australia on April 13, 2014.

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41 photos: The search for MH370
The HMS Echo, a vessel with the British Roya; Navy, moves through the waters of the southern Indian Ocean on April 12, 2014.

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41 photos: The search for MH370
A Royal Australian Air Force AP-3C Orion, on a mission to drop sonar buoys to assist in the search, flies past the Australian vessel Ocean Shield on April 9, 2014.

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41 photos: The search for MH370
A relative of a missing passenger cries at a vigil in Beijing on April 8, 2014.

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41 photos: The search for MH370
Australian Defense Force divers scan the water for debris in the southern Indian Ocean on April 7, 2014.

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41 photos: The search for MH370
A towed pinger locator is readied to be deployed off the deck of the Australian vessel Ocean Shield on April 7, 2014.

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41 photos: The search for MH370
A member of the Royal New Zealand Air Force looks at a flare in the Indian Ocean during search operations on April 4, 2014.

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41 photos: The search for MH370
On March 30, 2014, a woman in Kuala Lumpur prepares for an event in honor of those aboard Flight 370.

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41 photos: The search for MH370
The sole representative for the families of Flight 370 passengers leaves a conference at a Beijing hotel on March 28, 2014, after other relatives left en masse to protest the Malaysian government’s response to their questions.

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41 photos: The search for MH370
A member of the Royal Australian Air Force is silhouetted against the southern Indian Ocean during the search for the missing jet on March 27, 2014.

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41 photos: The search for MH370
Flight Lt. Jayson Nichols looks at a map aboard a Royal Australian Air Force aircraft during a search on March 27, 2014.

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41 photos: The search for MH370
People in Kuala Lumpur light candles during a ceremony held for the missing flight’s passengers on March 27, 2014.

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41 photos: The search for MH370
Malaysian Prime Minister Najib Razak, center, delivers a statement about the flight on March 24, 2014. Razak’s announcement came after the airline sent a text message to relatives saying it “deeply regrets that we have to assume beyond any reasonable doubt that MH 370 has been lost and that none of those onboard survived.”

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41 photos: The search for MH370
Grieving relatives of missing passengers leave a hotel in Beijing on March 24, 2014.

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41 photos: The search for MH370
A passenger views a weather map in the departures terminal of Kuala Lumpur International Airport on March 22, 2014.

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41 photos: The search for MH370
A Chinese satellite captured this image, released on March 22, 2014, of a floating object in the Indian Ocean, according to China’s State Administration of Science. It was a possible lead in the search for the missing plane. Surveillance planes were looking for two objects spotted by satellite imagery in remote, treacherous waters more than 1,400 miles from the west coast of Australia.

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41 photos: The search for MH370
Satellite imagery provided by the Australian Maritime Safety Authority on March 20, 2014, showed debris in the southern Indian Ocean that could have been from Flight 370. The announcement by Australian officials raised hopes of a breakthrough in the frustrating search.

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41 photos: The search for MH370
Another satellite shot provided by the Australian Maritime Safety Authority shows possible debris from the flight.

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41 photos: The search for MH370
A distraught relative of a missing passenger breaks down while talking to reporters at Kuala Lumpur International Airport on March 19, 2014.

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41 photos: The search for MH370
On March 18, 2014, a relative of a missing passenger tells reporters in Beijing about a hunger strike to protest authorities’ handling of information about the missing jet.

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41 photos: The search for MH370
U.S. Navy crew members assist in search-and-rescue operations in the Indian Ocean on March 16, 2014.

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41 photos: The search for MH370
Members of the Chinese navy continue search operations on March 13, 2014. After starting in the sea between Malaysia and Vietnam, the plane’s last confirmed location, search efforts expanded west into the Indian Ocean.

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41 photos: The search for MH370
A Vietnamese military official looks out an aircraft window during search operations March 13, 2014.

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41 photos: The search for MH370
Malaysian air force members look for debris near Kuala Lumpur on March 13, 2014.

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41 photos: The search for MH370
Relatives of missing passengers wait for the latest news at a hotel in Beijing on March 12, 2014.

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41 photos: The search for MH370
A member of the Vietnamese air force checks a map while searching for the missing plane on March 11, 2014.

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41 photos: The search for MH370
A Vietnamese air force plane found traces of oil that authorities had suspected to be from the missing Malaysia Airlines plane, the Vietnamese government online newspaper reported on March 8, 2014. However, a sample from the slick showed it was bunker oil, typically used to power large cargo ships, Malaysia’s state news agency, Bernama, reported on March 10, 2014.

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41 photos: The search for MH370
A U.S. Navy Seahawk helicopter lands aboard the USS Pinckney to change crews on March 9, 2014, before returning to search for the missing plane in the Gulf of Thailand.

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41 photos: The search for MH370
Buddhist monks at Kuala Lumpur International Airport offer a special prayer for the missing passengers on March 9, 2014.

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41 photos: The search for MH370
Members of a Chinese emergency response team board a rescue vessel at the port of Sanya in China’s Hainan province on March 9, 2014.

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41 photos: The search for MH370
The rescue vessel sets out from Sanya in the South China Sea on March 9, 2014.

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41 photos: The search for MH370
Malaysian Prime Minister Najib Razak, center, arrives to meet family members of missing passengers at the reception center at Kuala Lumpur International Airport on March 8, 2014.

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41 photos: The search for MH370
A relative of two missing passengers reacts at their home in Kuala Lumpur on March 8, 2014.

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41 photos: The search for MH370
Chinese police at the Beijing airport stand beside the arrival board showing delayed Flight 370 in red on March 8, 2014.

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41 photos: The search for MH370
Malaysia Airlines Group CEO Ahmad Juahari Yahya, front, speaks during a news conference at a hotel in Sepang on March 8, 2014. “We deeply regret that we have lost all contacts” with the jet, he said.

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Pings & things
On April 5 and 8 of 2014, hopes were raised again when signals believed to be from the missing aircraft’s data recorders — so-called black boxes — were detected near an arc where an Inmarsat satellite had last communicated with the plane.

12 photos: Remembering the passengers of MH370

12 photos: Remembering the passengers of MH370
There is still no way to know for sure why Flight MH370 ended, but we are learning more about the lives of those on board. CNN is remembering them through snapshots shared with us.

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12 photos: Remembering the passengers of MH370
Rodney and Mary Burrows were looking forward to becoming first-time grandparents after their return home to Australia.

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12 photos: Remembering the passengers of MH370
Australians Catherine and Robert Lawton were traveling with friends on vacation when the flight disappeared.

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12 photos: Remembering the passengers of MH370
Paul Weeks was traveling to Mongolia for a new job as an engineer. His wife says Paul left behind his watch and his wedding ring before the trip, in case anything happened to him while he was away. Anderson spoke with Paul’s brother & sister who said they are coping by spending time together as a family.

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12 photos: Remembering the passengers of MH370
Chandrika Sharma, left, was on Flight 370; her daughter Meghna and husband K.S. Narendran wait patiently, trying to manage their anxiety and longing for her return.

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12 photos: Remembering the passengers of MH370
Muktesh Mukherjee and Xiaomo Bai had been vacationing in Vietnam and were on their way home to their two young sons in Beijing.

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12 photos: Remembering the passengers of MH370
76-year-old Liu Rusheng, an accomplished calligrapher and one of the oldest passengers on the flight, was in Malaysia to attend an art exhibition with his wife.

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12 photos: Remembering the passengers of MH370
Teens Hadrien Wattrelos and Zhao Yan are shown in a photo on Wattrelos’ Facebook page. The photo is captioned, simply, “I love you,” in French.

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12 photos: Remembering the passengers of MH370
Firman Chandra Siregar, 24, studied electrical engineering in Indonesia and was on his way to Beijing on board Flight 370 to start a new job at an oil company.

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12 photos: Remembering the passengers of MH370
Patrick Francis Gomes, center, was the in-flight supervisor for the missing plane. His daughter describes him as a quiet person with a sense of humor.

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12 photos: Remembering the passengers of MH370
Ch’ng Mei Ling, a Malaysian citizen who lives in Pennsylvania, is a process engineer at a chemical company.

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12 photos: Remembering the passengers of MH370
We do not have photos of all 239 passengers, but we wanted to remember that there are loved ones around the world missing them right now. View CNN’s complete coverage of Flight 370.

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These signals, or pings, turned out to be another false lead, when on May 28 a U.S. Navy official told CNN that authorities had come to believe the pings did not come from the onboard data or cockpit voice recorders but instead came from some other man-made source unrelated to the jetliner.

Unexplored ocean floor It’s not just shipwreck parts and pieces and pings searchers in the area have found. As ships surveyed tens of thousands of square miles of the bottom of the ocean where the plane is believed to have gone down, Australian searchers reported extinct volcanoes, immense ridges and cavernous trenches discovered on the seabed by experts mapping the underwater terrain with state-of-the-art equipment.

The depth and seafloor terrain of this area of ocean was largely unknown before the search for the plane drew attention to it.

What’s next? According to the latest operational search update from the Australian Transport Safety Bureau’s Joint Agency Coordination Centre issued March 2, more than 85,000 square kilometers (3,2818.68 square miles) of the seafloor have been searched so far. As agreed to in April 2015, 120,000 square kilometers will ultimately be thoroughly searched. It is anticipated this will be completed around the middle of the year, according to the update. The ships Fugro Equator and Havila Harmony continue to conduct various underwater search operations. The ship Fugro Discovery arrived back in the search area on February 25 to join them.

If search teams find the plane, Australia, Malaysia and the People’s Republic of China have agreed to plans for recovery activities, including securing all the evidence necessary for the accident investigation. If no credible new information is found in the current search area, the governments involved have agreed that there will be no further expansion of the search.

CNN’s Rene Marsh, Don Melvin, Ashley Fantz, Faith Karimi, Pamela Boykoff and Ben Brumfield contributed to this report.

Source: What the search for Flight 370 has found (that’s not the plane)