A trident has three prongs or teeth, as the root dent, "tooth", tells us. The trident has long been used to spear fish in different parts of the world, so there's no mystery about why the Greek sea god Poseidon and his Roman counterpart Neptune both carry a trident as their symbol. In some gladiator exhibitions in ancient Rome, one gladiator, called a retiarius ("net man"), would be equipped as though he were a fisherman, with a weighted net and a trident; with his net he would snare his sword-wielding opponent, and with his trident he would spear his helpless foe.