What the heck is that anomaly on sonar images from the floor of the Pacific Ocean? According to researchers from The International Group for Historic Aircraft Recovery (TIGHAR), it could be the wreckage of Amelia Earhart's airplane from 1937.

Earhart, the first woman to fly solo across the Atlantic Ocean, disappeared over the Pacific Ocean in 1937 during an attempt to circumnavigate the globe. Last year TIGHAR — which has been searching for evidence to explain the aviator's disappearance for several years now — conducted two expeditions to the remote Pacific island of Nikumaroro, where they think she may have crash-landed. The expedition used underwater robots and other technology and did not produce any conclusive evidence at the time, in part because technical issues and weather conditions thwarted some of their efforts.

But while reviewing the data from the expedition, TIGHAR researchers noticed something they had missed: "a sonar image...that could be the wreckage of Amelia Earhart's Lockheed Electra. It looks unlike anything else in the sonar data, it's the right size, it's the right shape, and it's in the right place," the organization's website proclaims.

The object is about 22 feet long in waters about 600 feet below the surface. TIGHAR was actively looking just a few hundred feet from where the anomaly lies, so they did not see it until reviewing the data this March. It was actually spotted by someone online, as recounted on the TIGHAR website:

"It wasn't until March 7, 2013, that Richard Conroy, a member of TIGHAR's on-line Amelia Earhart Search Forum, spotted the anomaly in a sonar map that was included in the Niku VII report in TIGHAR Tracks. Richie has no training in interpreting sonar images but that was probably his biggest advantage. Once you know what to look for, the anomaly is painfully obvious. It gives the impression of being an object that struck the slope at the base of the second cliff at a depth of 187 meters (613 feet), then skidded in a southerly direction for about 40 meters (131 feet) before coming to rest."

Ric Gillespie, TIGHAR's executive director, told Discovery News that the group hopes to raise another $3 million to conduct another expedition to the island.

ABC News filed this video report, with images from the expedition and interviews with Gillespie and other Earhart experts: