Large Platyostoma Gastropod with Crinoid Holdfast

This is large Platyostoma niagarense gastropod from the Waldron Shale of Indiana. It's Silurian in age or approximately 430 million years old. This specimen has been prepared using air abrasives and air scribe techniques under microscope to extract it from the surrounding limestone. There is a crinoid holdfast attached to the back side of it making for an interesting association.

Gastropods which are more commonly referred to as snails have been around since the Late Cambrian period. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. There are 611 families of gastropods, of which 202 families are extinct and appear only in the fossil record.