In Greek myths, Poseidon's trident was forged by the cyclopes.
Poseidon wields his trident on a number of occasions. He used his trident to strike a rock upon the hill of the Acropolis, producing a well of seawater, in what developed into a contest between him and Athena over possession of Attica. When he lost, Poseidon used the trident to dry out the land so they had no water. The well was later to be called the Erechtheis. There is further myth that Poseidon (Neptune) produced a horse by striking the earth with the trident, in order to bolster his claim,but there is no attestation for this among Greek writers. The alleged trident print on a rock and the sea well within the Erechtheion were witnessed by the geographer Pausanias while visiting Athens.