Rostrum

Rostrum, the beck or spur of an ancient galley, placed on a level with the water. It protruded in front of the prow, and was armed with a sharp point of copper or of iron. It was almost exclusively used in ships of war (thence denominated Rostratae naves), to render them more formidable near enough to strike, they frequently sank, by piercing a hole through the side, and letting in the water. 
The figure of these rostrated vessels occurs frequently on Roman coins, both consular and imperial.
There is a denarius of Pompey the Great, bearing on its reverse a galley with a legionary eagle on its rostrated prow, and with oars and rudder; its stern ornamented with the aplustrum, and on the deck a tower stands, surmounted by the figure of Neptune, who holds the tridentin his right hand, and plants his left foot on a rostrum. Round this type are the words MAG. PIVS. IMP. ITER.
That, in the earliest times of the Romans, coins were struck with the prow and beak of a ship appears from Pliny (1. xxxiii. c. 3), Nota aeris fust ex altera parte Janus geminus; ex altera rostrum navis; in tridente vero et quadrante rates.
See Prora navis; also the As and its parts.
On the rostrum of a ship Minerva Jaculatrix stands, in gold and silver coins of Domitian.
A silver medal of Augustus also exhibits the prow of rostrated galley, on which a naval trophy is fixed, together with a rudder and anchor placed transversely; the inscription is CAESAR. DIVI. F.

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