This is an exact model of a Boy on a Dolphin ancient Greek coin

 originals were minted in Taras Calabria, a Greek occupied region in southern Italy,

 during the time period of 334 to 231 BC 

 The coin features a boy riding a dolphin on one side and a horseman on the other

  In Greek mythology the tale goes that Taras,

 the son of the Greek sea god Poseidon, was rescued from a shipwreck by a dolphin

sent by Poseidon to rescue him

The other side is a man on horse, it is said to  believe that those horses were meant to

represent the games at the hippodrome, where athletes competed with each other

 in contests of equestrian skill and strength