The Monster That Challenged the World 1957 colorized (Tim Holt) by Gramercy Pictures

An earthquake in the Salton Sea unleashes a horde of prehistoric mollusk monsters. Discovering the creatures, a Naval officer (Tim Holt) and several scientists (Hans Conried, Max Showalter) attempt to stop the monsters, but they escape into the canal system of the California's Imperial Valley and terrorize the populace, including Audrey Dalton and Barbara Darrow.