Cf. Cr 56/3 Æ Semis, overstruck, after 211 BC
Roman Republic Æ Semis(24mm, 10.52g, 2h). Anonymous, after 211 BC. Mint in Southern Italy, Sardinia or Sicily. Laureate head of Saturn right, S behind/Prow of galley right, S above, ROMA below. Overstruck on unknown Roman Æ. Cf. Crawford 56/3. McCabe Group H1(Anonymous halfweight overstrikes).
Ex RBW Collection
This coin is lightweight and obviously overstruck on some sort of Roman bronze. The overtype may even be imitative, and I am not 100% certain of my attribution but it's the closest thing I've got.