It's an important find because experts think something went wrong with the wing to cause the craft to break up.
Nasa are still not sure where the 46-cm (18-inch) bit of the wing belongs.
But it does have some carbon-carbon tiles on it, the special tough material that covers the leading edge of a wing.
That bit gets the hottest as shuttles re-enter the atmosphere.
Debris, scattered across very large distances, are being collected and pieced together to give Nasa clues to the tragedy.
Investigators are looking at several clues and possibilities to help them find out what happened:
All seven astronauts died when Columbia broke up on re-entry to Earth's atmosphere on 1 February.