In Greek mythology, what was the name of a monster also known as a 'sea-horse'?

The hippocampus or hippocamp, also hippokampos (plural: hippocampi or hippocamps; Greek: ἱππόκαμπος, from ἵππος, "horse" and κάμπος, "sea monster"), often called a sea-horse in English, is a mythological creature shared by Phoenician, Etruscan, Pictish, Roman and Greek mythology, though its name has a Greek origin. The hippocampus has typically been depicted as having the upper body of a horse with the lower body of a fish.

Coins minted at Tyre around the 4th century BC show the patron god Melqart riding on a winged hippocampus and accompanied by dolphins. Coins of the same period from Byblos show a hippocampus diving under a galley.

A gold sea-horse was discovered in a hoard from the kingdom of Lydia in Asia minor, dating to the 6th century BC.