If the flight data recorder [aka "black box"] from missing Malaysia Airlines Flight 370 were found, it will still work -- despite being underwater for more than a year, experts say. After an airplane wing was found washed up Wednesday on Reunion Island in the Indian Ocean, experts and authorities have tried to determine whether the debris is from Flight 370 -- and if so, whether it holds any clues to the plane's disappearance.

The only piece of evidence capable of pinpointing exactly why the plane went down, however, is the black box. Authorities have been searching for evidence of the plane since it vanished in March 2014, while traveling from Kuala Lumpur, Malaysia, to Beijing.

Black boxes are regarded as practically indestructible, so finding one from Flight 370 would be a major help to investigators. Black boxes are coated in a double layer of titanium or stainless steel, and researchers have tested them by shooting them out of an air cannon, dropping them from heights, submerging them in pressurized salt water, and even burning them at high temperatures for more than an hour, NBC News reported.

GettyImages-482269842 Authorities carry a piece of debris from an unidentified aircraft on Reunion Island in the Indian Ocean on July 29, 2015. Some believe the discovery may be part of the missing Malaysia Airlines Flight 370. Photo: Agence France-Presse/Getty Images

"It is extremely rare for a black box to be destroyed," said Scott Hamilton, director of Leeham Co., an aviation consulting firm. "Black boxes have traditionally outperformed their design," Hamilton said, as National Public Radio reported.

Black boxes typically store two types of information: the flight data of the plane's mechanics and an audio recording from the cockpit. The recording from the cockpit can store only two hours of conversation, so whether that would be enough to piece together the mystery of Flight 370 is unknown.

Finding the black box from the missing flight, however, could prove to be very difficult. After a black box hits the water, it gives off a beacon signal every second for 30 days, meaning that Flight 370's black box went silent more than a year ago.