A large gray oblong, oval shell with a single black central hole at the top of the shell, the portal through which waste products are released.
Gray, black, or brown slimy mantle (body wall) covering the shell, unlike any other limpet that has mantle under the shell.
Adult shell is 3-5 inches in diameter.
Sessile animal, permanently attached to rocks.
Monterey, California to Baja California, Mexico.
Live in the intertidal zone.
Found at depths up to 108 feet.
Reproduce by broadcast spawning.
Embryos develop into planktonic larvae and then juvenile veligers (tiny larvae with cilia to move in water) before settling somewhere permanently and growing into adult form.
Filamentous cyanobacteria, diatoms, brown and red algae such as seaweed, seagrass, foraminifera, hydrozoans, bryozoans, nematodes, bivalves, gastropods, crustaceans, and tunicates.
People use this species for medicinal uses.
The primary predators for limpets are sea stars, birds, and the occasional crab.
This species is one of the largest keyhole limpets.
The whole on the top of the shell makes them different from true limpets, which release waste from the mantle beneath the shell.
The blood of this species is used in many cancer treatments and vaccines, as it stimulates the immune system and its protein transports molecules throughout the body.
A liter of blood from a keyhole limpet will produce 20 grams of protein, which can be worth as much as $100,000.
Their shells were used as currency among Native Americans.
Sources: Harris and Markl, 1999; Harvesting blood from limpets for a cancer vaccine; How mollusk blood could cure cancer; Marine Biology. 8th ed.; Encyclopedia of Life; CaliforniaTidePools.com; sealifebase