Originally the maiden Caenis, changed by Poseidon into a supposedly invulnerable fighter. Caeneus angered Zeus by walking into the marketplace one day and demanding that his spear be worshipped as a god. Determined to punish this sacrilege, Zeus had to give careful thought to bringing about the demise of a fighter who could not be killed in combat. He achieved his end by turning the centaurs against Caeneus. They killed him by pounding him into the ground.