Abrasion from sand and wave action can also fade and wear shells. Mineral oil is one way to hightlight a shell's color without seriously damaging the shell. Next Question 13. Giant tridacna clams do not poison people, or anything else for that matter. They eat algae.
Some cones have a harpoon that can give a lethal injection.
They have killed people. Some octopus also have a potent venom that can cause death to humans. There are no known mollusks lethal to humans in waters around the United States of America. Next Question 12. Murex shells are capable of drilling through a clam shell to have a clam dinner.