The ocean sunfish ("Mola mola", also called the mola or sun fish) is a large ocean fish found in warm and temperate oceans. It is the heaviest known bony fish in the world. It has an almost circular, flattened body. This unusual fish swims by flapping its long pectoral and dorsal fins; the caudal fin is used as a rudder (for steering). Some sunfish have been seen floating on their sides at the top of the sea; they may be using the sun to heat themselves up. They eat crustaceans, starfish, jellyfish, sponges, mollusks, algae, plankton, squid, and small fish.