Limpets on the rocky shores of California are well known to travel across
the rocks to graze on algae. They return to a particular home site before
each low tide. So when the tide is down, you always see them "at home"
digesting their meal. The California rocks are mostly rather soft; the
grains of quartz and other minerals are only loosely cemented by calcium
carbonate, and the limpets loosen the grains further by grazing with their
radulae. The pits are shallow and oval, about the same size and shape as
the underside of a limpet, and they may cover one whole side of a rock. See
"Between Pacific Tides" or some other book on seashore life of California.
Perhaps one of our Californian Conchlers can suggest a book at a more
appropriate reading level?
 
Andrew K. Rindsberg
Geological Survey of Alabama