Fossil Gastropod (Cyclonema) With Bryozoan - Ohio

This is a nice piece from the Late Ordovician, Arnheim Formation of Ohio. There are two nice specimens of the gastropod Cyclonema present along with some bryozoans. Mollusc shells are typically composed of a phosphatic substance called Aragonite. Unfortunately Aragonite does not preserve well in the Cincinnatian, so most gastropod fossils are internal molds, unlike this specimen. THis piece has been cleaned under microscope using air abrasives.