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Marine Fossils and their Living Relatives

Fossil: Rock snail 
Murex sopenahensis 

This fossil murex snail is 40 million years old, from a time when the whole world was much warmer than it is today. In the Washington region, palm trees grew on the western coastal plain, and plants of the banana and magnolia families grew on the eastern highlands. At this time most of western Washington was underwater and the present location of Interstate 5 would have been beachfront. The area was washed by warm subtropical seas with a very high diversity of marine invertebrates. But within a few million years the global climate became much cooler and along our coast many of these tropical snails became extinct.

Today's tropical murex snails are collectors' items because of the shells' elaborate ornamentation in the form of ridges, frills, knobs, and projections, especially around the aperture—where the soft-bodied snail comes in and out of its shell. Similar ornamentation is found in the fossil forms. These types of shell protect the snail from their predators—fish and crabs—by making it more difficult to crack the shell or to pull the body out of the shell. Murex snails are carnivorous and drill holes in the shells of their prey, usually clams. The robust shell ornamentation is especially important for carnivorous snails because they must actively seek prey in competition with the crabs and fishes.

murex sopenahensis
Forty million years old, Murex sopenahensis is one of the rare murex shells from western Washington. 3 cm tall.
Photo by Ron Eng

leafy hornmouth
Leafy hornmouth (Ceratostoma foliata).
Photo courtesy of Shorekeepers' Guide, Fisheries and Oceans Canada

Leafy hornmouth snail 
Ceratostoma foliata

The leafy hornmouth snail can be found on rocky intertidal beaches and down to depths of 200 feet on the Olympic Peninsula coasts. These common snails in the murex family are carnivorous and prey on other animals, especially clams.

Leafy hornmouth snails congregate to reproduce in late February and March. They lay clusters of yellow egg capsules on rocks, each containing 25–80 eggs. The adult snails often remain with the eggs to guard them until they hatch. The larval stage is passed inside the egg, and the young emerge as small snails. These snails can be destructive to commercial oyster and mussel beds.