Fossil shown is actually 6 inch wide, and found as a boulder on the beach. This is the second half of a mudstone nodule, and contains the actual fossil not the trace fossil.

Identification can be obtained in part via the style of ribbing on the shell, and helped greatly by knowing the age of area found. Species can be used for zoning, to help identify a specific location and specific time.

Evolute is laterally compressed with quadrate whorl section and tricarinate and bisulcate venter with falcate ribs.