Fossil shown is 3 inches in length and found inside a much larger rock (fossil was not visible), found as an erratic on the beach. Fossil is iron rich and heavier than average.

Identification can be obtained in part via shape and style of ribbing on the shell.

Knowing the age of the rock and area were found always helps; different species live at different times helping in identify

Species can be used for zoning, to help identify a specific location and specific time.