Coin depicted roughly twice actual size*

As of Marcus Aurelius

Bronze as, 26mm, 10.32gm, issued AD 176/177 Rome mint.

Obv: M ANTONINVS AVG GERM SARM TRP XXXI, Laureate head right.

Rev: IMP VIII COS III FELICITATI AVG PP S C, Galley with four rowers, facing left; on the stern, Neptune, standing left, his foot on a rock, holding trident.

References: Sear 5061, RIC 1192.