mm43,
It has been mentioned before, but what it was I have no idea. My feeling was that it had broken free from the wreckage after it had sunk, and then slowly made its way back to the surface. If it had been on the surface for say 3 days when found, the backtracked current vector (no leeway for windage allowed) would place it near 2°50'N 31°10'W. If it had left the aircraft while it was airborne - anywhere??
After looking at 8U771, the biggest piece may one of the engines.
BS