The Roman god Neptune corresponds to the Greek god of water Poseidon and was originally probably the god of flowing water, bubbling springs or even the weather. From the beginning of the 3 century B.C. Chr. he was equated with the Greek Poseidon, which also made him the god of the sea.

He is usually depicted with a trident, sea creatures and/or dolphins. With the earthquake-triggering trident, a gift from the Cyclops, he could rule the sea, rivers, and lakes. The dolphins serve him as messengers. He is often accompanied by horses that have the shape of fish tails behind.

In the most common cases he wears a beard and has a narrow ribbon tied in his hair. In his hand he holds his trident. He often stands on a shell - instead of a chariot - drawn by sea-horses. Sometimes there are four, which can take him in all four directions. Not infrequently he is shown alone, standing in a still sea, surrounded by dolphins, and contemplating a richly laden ship.

Neptune, like other deities, was occasionally minted as a motif with attributes typical of him on the reverse of Roman coins.