Sea anemones! (Say “anemone” 5 times fast!”)
Anthozoans also include corals:
Often called “true jellyfish” but… first of all….they are not FISH! It’s more appropriate to call them “jellies!”
BEWARE! These have a venom that results in excruciating pain! If it’s a large sting area, an untreated victim may die in as little as 3 minutes!