3.6" Fossil Brachiopod (Spirifer) On Matrix Of Crinoid Stems

This is a 3.6" plate of a brachiopod fossil (Spirifer grimsi) from The Burlington Formation, Ralls County, Missouri. Crinoid and shell fragments are also visible.

Brachipods have two hard shells (valves), on one top and the other bottom unlike bi-valve mollusks (clams and mussels) who have their shells arranged left and right. These valves can be opened or closed for feeding or protection.