Lamp Shell Terebratulina septentrionalis
It would be easy to mistake a lamp shell for a small bivalve mollusk, as both have a hinged shell in two parts and live attached to the sea floor. Lamp shells, however, have a very thin, light shell and the two parts are different sizes, with the smaller one fitting into the larger. The shell valves cover the dorsal and ventral surfaces of the animal whereas in bivalve mollusks they are on the left and right side of the body. Lamp shells attach their pear-shaped shell to hard surfaces by means of a fleshy stalk that emerges from a hole in the ventral shell valve. With the shell valves gaping open, the animal draws in a current of water that brings plankton with it. Taking up most of the space inside the shell is a feeding structure called the lophophore, which consists of two lateral lobes and a central coiled lobe covered in long ciliated tentacles. The beating of the cilia creates the water current. Lamp shells are found worldwide, but they are especially abundant in colder waters. In the northeastern Atlantic, Terebratulina septentrionalis is mostly found in deep water, while along the east coast of North America, it commonly occurs in shallow water. This species is very similar to Terebratulina retusa.