Archimedes sp.

Mississippian

Borden Formation

Big Hill, KY USA.

Excellent 231mm slab with 5 Archimedes, longest is 135mm.

Bryozoan.

Archimedes is a genus of fenestrate bryozoan which lived in colonies.  It is almost always found as fragments, screw-shaped parts of a mesh no longer connected to the central body.  It lived from the Mississippian to Permian of North America, Europe, and Australia.