Mamertini, Messana, Sicily, AE pentonkion. 18mm, 210-200 BC. 4.12 g. 

Laureate head of Zeus right.
MAMERTINWN, Helmeted warrior standing right, wielding
spear and holding shield on left arm. P in right field.

BMC 31; Calciati 51; Hoover HGC 858; McClean 2448; Särström 405-418. 

With permission of Numismatica Ars Classica, May 2004.
Estimate: CHF 400.