Even a piece of metal can get a second chance. In 1991, a group of researchers investigating the disappearance of Amelia Earhart found a sheet of aluminum on the island of Nikumaroro in the Western Pacific. Earhart's plane, a Model 10 Electra, mysteriously vanished near the island on July 2, 1937. This piece of metal, a sheet 19 inches by 23 inches and made of the same material as Earhart's plane, looked like it could be the first piece of the aircraft ever found.

The problem was its odd shape and size, which didn't seem to fit any part of the Electra. "We finally reached the point that we decided that it couldn't be from Earhart's plane," said Richard Gillespie of The International Group for Historic Aircraft Recovery, which has spent 26 years and made 10 expeditions to investigate the mystery surrounding Earhart's disappearance.

The team then looked at every other kind of plane that could've flown over the Pacific at that time. But, again, nothing fit.

"Earlier this year, around June, I threw up my hands," Gillespie said. "I didn't know what the heck this thing is."