The hippocamp (also: hippocampe, hippokamp, or hippocampus, pl: hippocampi or hippokampoi) is a sea monster in Greek mythology. The creature has a horse's body and a fish's tail. It was not commonly pictured in Classical Greek art but when it is, it is sometimes ridden by the sea god Nereus or sea nymphs. The hippocamp plays no part in any known mythological tale. The ancients believed it was the adult form of the seahorse. It draws the chariot of Poseidon and other sea divinities in the works of ancient writers and artists.