Athearnia crassa
Athearnia crassa, the boulder snail, was a species of freshwater snail in the family Pleuroceridae.
Description
The shell is either conical or globose in shape and possesses a ponderous structure. It consists of five whorls, which are either flat or slightly convex. The spire is notably exserted, and the aperture is ovate, featuring a well-marked columellar notch. The outer lip is thick, and the overall color of the shell is brown.The specimen typically reaches a length of 3 inches and its habitat is the Clinch River in Tennessee. This species differs from Anculosa praerosa by its more highly developed spire and its more distinct notch.