Is this a limpet?
Today I saw this on a rock at Ellwood Beach. Perhaps it is a common creature, but I have never seen one before. There were only two on the same rock. Sorry I didn't think to put a coin beside it for size comparison, but I think you can judge the size by the mussels right next to it. Thank you for i.d. and much obliged.
Yes, this is a limpet! It is Lottia gigantea, the Giant Owl Limpet.
Incidentally, Lottia gigantea is territorial and will drive other limpets out of its territory at a "ramming speed" that is notably faster than its grazing speed. Check out the beginning of this video from a research group at Chapman University. You will want to have the sound on to hear the voices of excited scientists cheering on a limpet. Moving at speed tires these animals out, and the researchers are looking into how that can make them vulnerable to being knocked off the surface to which they cling.
Thank you for sharing your photo with us.
Curator and Howard/Berry Chair of Malacology Henry W. Chaney, Ph.D.