Poseidon on Brundisium semis
Zeus' brother (Roman Neptune), master of the seas and god of earthquakes. His main attribute is the trident, and he is often represented on the prow of a ship or with a foot on a rock, sometimes accompanied by dolphins. In other respects, his physical appearance usually resembles that of his brother - indeed, one of the finest Classical Greek bronze statues, discovered off Cape Artemision in this century, still baffles the experts regarding its identity, as the key object the god is hurling - thunderbolt or trident - is missing. Perhaps, the very fact that he emerged from the sea seems to tip the scales to Poseidon, in a slight majority of opinions.
Search for coins with Poseidon reverses.