Here's what my sister said about the Anzio piece: It's an impression stamped into ceramic material that has been glazed. Another sister has the original stamp, which is about 3 or 4 inches long—a metal stamp with a wooden handle.

My hunch is that my father made the metal stamp and ceramic piece. Making a stamp for just one ceramic piece is unlikely, so there must have been more produced. Dad was an experienced machinist and jig maker before the war, and he had access to tools during the war as well. After the war, he worked in a factory that was equipped with machinist tools and kilns to fire ceramic insulators. Unfortunately, anyone in the family that could shed some light on this is long gone.

Sandy (a.k.a. Peanuts)

Interesting tidbits! Thanks for the input.