Cambrian Inarticulate Brachiopod

A Cambrian inarticulate brachiopod, Lingula sp., from the Cambrian Conasauga Formation. This type of brachiopod is termed "inarticulate" because its upper and lower shells do not remain "articulated" after death. They are held together only by muscles and do not have the hinge typical of such familiar bivalves as clams and scallops.

Close-up photograph of two dark fossilized inarticulate brachiopod shells embedded in a light-colored rock surface.
Close-up photograph of two dark fossilized inarticulate brachiopod shells embedded in a light-colored rock surface.