Crepidula ustulatulina can be distinguished from other species of
Crepidula by the following suite of characters. The shell is small (usually less than 1.5 cm), smooth, and convex. It is often cream with distinct chestnut brown spots or streaks, sometimes it is brown overall with darker spots or streaks. The internal septum is flat and white, and the animal's left side usually extends somewhat farther forward than does the right side. The margin is straight or slightly bowed. There is an oval muscle scar just anterior to the shelf on the animal's right side. The small apex is usually directly posterior and is slightly rostrate in animals living on small snails but not in those from flat substrates. The external body color is light to dark gray with opaque white or cream on the tips of the tentacles and the lips. There are usually large yellow pigment splotches on the mantle, neck and sometimes foot, visible only in life. The maximum recorded
shell length is 13.2 mm. The shell is usually cream with brown mottling. The visible soft parts are mostly grey. ==Habitat==