GIA4699833 For a long time it was believed that this bas-relief represented a man breathable under water thanks to the air contained in a skin surface. It is now believed that he is a swimmer supported by an outboard serving him as a buoy - bas-relief, Mesopotamia, 7th century BC. by Mesopotamian, (7th century BC); Private Collection; (add.info.: For a long time it was believed that this bas-relief represented a man breathable under water thanks to the air contained in a skin surface. It is now believed that he is a swimmer supported by an outboard serving him as a buoy - bas-relief, Mesopotamia, 7th century BC.); by Giancarlo Costa; out of copyright.