are there any dangerous sea shells?
yes - cone shells!
There are more than 300 species in this large family. They are found from deep water to the shallowest intertidal zone, from rocky to coral reef habitats, throughout the tropical and warmer oceans of the world.
They have the basic shape of an ice cream cone, (so if it looks like an ice cream cone, leave it alone!) with a long and narrow aperture with a thin sharp outer lip, and a flat or spiral top.
Many species are attractively coloured and sought after by collectors, however, they are one of the few seashells potentially fatal to humans.
Cones are carnivorous, being active predators on marine worms, fish and even other shells. Their hunting weapon is their modified radula (normally a feeding tool that scrapes food off the substrate). This sits inside a modified salivary gland soaking in poison. This tooth has evolved into a harpoon with a hollow, barbed shaft through which venom is injected. The radula is located on the end of a proboscis that is pushed out of the mouth and extends out of the shell. The prey is dragged into the expandable proboscis sheath to be digested.
The molluscivorous species may use their muscular foot to drag the dead mollusc prey from its shell and the piscivorous (fish-eating) species usually have wider apertures to accommodate their larger prey.
Cone shells are best known for the fact that many of the larger species that hunt fish and larger molluscs are capable of causing pain, paralysis, and even death in humans.
Therefore, live shells should never be picked up. There is no safe way to pick them up with the naked hand, as the proboscis can extend out in several species.
There are at least two species that have cause fatalities and at least half a dozen other potentially painful species include. Because of the similarity between species, it is difficult to distinguish the dangerous species from the not-so-dangerous, so it is best not to pick up any living specimens in or near water.
Luckily for shell admirers, many specimens wash up on tropical beaches once the animal has died, although they may fade considerably in the tropical sun.