Owl Limpets are a type of shellfish that live in the inter-tidal region of the California coast. We saw this Owl Limpet on the ocean floor near the low-tide level near Point Loma in San Diego. The inter-tidal region is the part of the shore that is between the tides. That is, at high tide the inter-tidal region is underwater, but at low tide the inter-tidal region is out of the water. We saw many Limpets both in and out of the water.
The Owl Limpet is the shell at the top left in this picture. An Owl Limpet has a muscular foot that holds its body and shell tightly to the rock. The Limpet can crawl slowly across the ocean floor, often traveling at night to find plants that it eats. Some Limpets return to the same spot on the rocks every day after a night of foraging. Limpets may grow very slowly, and may live as long as 15 years.
Also notice the Top Snail near the lower right of this picture.
Limpets that live in the inter-tidal region can have their shells eroded. That is, the same erosion that grinds rocks into smooth round shapes also grinds the shells of the Limpets. These Owl Limpets show this erosion, as their shells are scratched and worn, presumably by rocks and sand rubbing against the shells as the waves wash over the shells during tidal fluctuations.