Could you be thinking of cone shells? They can be quite deadly. Never been stung by one, only by Scorpion Fish and Portuguese Man-of-War, and of course stuck by sea urchins. The Man-of -War burns, but the Scorpion Fish really packs a wallop! Octopus and squid are delicious, sea urchin isn't bad, can't eat jellyfish (not even with peanut butter), but Scorpion Fish is one of the finest salt-water fish you can dine on. Tastes like fresh water bass.