嗄n earthquake in the Salton Sea unleashes a horde of prehistoric mollusk monsters. Discovering the creatures, a Naval officer and several scientists attempt to stop the monsters, but they escape into the canal system of the California’s Imperial Valley and terrorize the populace.嗄n earthquake in the Salton Sea unleashes a horde of prehistoric mollusk monsters. Discovering the creatures, a Naval officer and several scientists attempt to stop the monsters, but they escape into the canal system of the California’s Imperial Valley and terrorize the populace.