The object, believed to be the door of an aircraft, was discovered just south of the city of St Denis. It is said to have foreign writing on it and possibly some illustration.
The Malaysia Airlines plane from Kuala Lumpur to Beijing disappeared last March with 239 people on board.
The first piece of wreckage has gone to France, where investigators in the city of Toulouse will seek to establish if it came from MH370. It is believed to be a wing flap from a Boeing 777 - the same type of aircraft as the one that vanished. Investigators will begin work this Wednesday.
BBC WORLD NEWS