I found this film about giant snails on the loose in the Salton sea area slightly better than most programmer monster films of the late 1950's. The giant snails are a believable menace in that they are presented as no more dangerous than any other large aquatic predator such a shark or crocodile. They put a fight but can be killed with several well aimed shots from a pistol or a heavy axe. The real danger as pointed in the film, is that snails are extremely fecund, and if they were to enter the ocean , they could reproduce in enormous numbers thus creating ecological havoc. Anyone who has ever had a fish tank knows once you introduce one tiny snail, in a matter of couple of weeks you have hundreds. One odd aspect everyone seems to comment on is that snails look like caterpillars in snail shells. There is a type of aquatic insect larva that uses a discarded snail shell as armour, much like a hermit crab does. Perhaps someone involved with the film had seen these insect larvae and mistook them for snails.