Diodora cayenensis is a member of the family Fissurellidae. Its shell is conically-shaped and well elevated. The top of the shell has an ovate hole in it called the "keyhole" toward the anterior of the animal. D. cayenensis is exposed to air during low tides and therefore needs to draw water into the shell for respiration and excretion which is then expelled through the keyhole. The foot of cayenne keyhole limpet is used to move slowly across rocky surfaces and to create a strong suction to keep waves from washing the animal from the rocks.The exterior of the shell is characterized by closely arranged ribs of different sizes. The color of the shell is cream with eight darker radial rings that are usually purple in color. The interior of the shell is glossy white. The animal is white with brown and orange-brown spots that are darkest on the head and tentacles.