This scalloped transverse lampshell (Terebratalia transversa) can be identified by having a hump in the middle edge where the shells come together, which can look like a smile or frown depending on the positioning of the animal. This particular lampshell is very young so the curve is barely formed. The shells can have a ribbed surface texture as in this example, or a smooth texture. Lampshells are attached to where they are located by a stalk or peduncle. The transverse lampshell grows to about three inches (7.6 cm) across, and has a range from northern Alaska to northern Mexico.