Lobster
While lobsters appear today in marine wildlife books and fancy restaurant menus about as often
as crabs, that was not the case on ancient coinage. 
In fact, it is hard to identify with
certainty any such appearances. One notable exception are some small bronze issues of Priapos
in the region og Mysia in northwestern Asia Minor. Numismatic catalogs usually refer to these
as crayfish, though they reside in fresh waters, and
the claws visible on some of them would also seem to rule out their shrimp relatives.
For resolution, one might also turn to documentary evidence. Priapos, however, seldom
appears in that context - but its neighboring city on the Sea of Marmara southern coast,
Parion, does more often. Specifically,
in his entertaining 3rd century work entitled Dining Scholars, the Greek writer
Athenaios from Naukratis, when discussing gastronomy, claims that "big mussels come from Ainos,
oysters from Abidos, Parion has crabs, and Mytilene scallops...". And
so that brings us back to the crustacean world once again, though in the more familiar form of crabs...