IncongruousArk (Anadara brasiliana)

SHELL LENGTH: Approximately 1-2 inches (2.54 - 5.08 cm)

Arks are one of the most abundant shells found on the beach ranging from 1/2 inch to 4 inches in size. They are easily recognizable by linear ribs on the outside, running from the hinge to the outer edge of the shell. The straight hinge is marked with small teeth, sometime referred to as a piano-hinge. Two round scars may be visible inside where the adductor muscles once attached. A mantle scar also may be visible, which is a slightly raised white area extending almost to the periphery of the shell. Living arks are covered with a hairy periostracum, as many shells are, and are found buried in sediment in tidal flats and in deep offshore waters. More than ten species of arks are found in the Carolinas and differ slightly by the number of teeth found on the hinge. Many arks will be found with small holes in them, which are perfectly beveled. These holes are good indicators of how the mollusk died. Atlantic Moon Snails use a toothed appendage called a radula to drill a hole in the shell, which kills the animal inside, allowing the Moon Snail to devour a meal.