Atrypa reticularis from Lockport, NY

Atrypa reticularis is an ubiquitous fossil from the Silurian through the Devonian. Near Lockport, NY I found some in the Irondequoit limestone Rochester Shale. The shells are typically large but almost always flattened as though through a laundry wringer.

Here is a typical specimen with nice detail preserved but when viewed from the side it's only a millimeter or two in thickness.

The flattened nature of the shells tends to cause them to break easily so finding one this large, with only a small chip missing, is somewhat rare for the site.

The Irondequoit limestone Rochester Shale is Silurian (Sheinwoodian) in age.