Analysis: BBC's transport correspondent Richard Westcott
Experts should be able to tell fairly quickly if this is a piece of MH370. Aircraft parts have individual serial numbers on them, and the airlines should have records of all those numbers.
So in theory, investigators could check them and give a positive or negative ID. If it is part of the aircraft, it's washed up thousands of miles from where search teams continue to look for debris at the bottom of the sea.
And realistically, although it would confirm the aircraft crashed and broke up, a piece of wing is unlikely to reveal much more about what actually happened on board the plane.
But these are all big "ifs" right now. It could still be yet another false alarm.