Oh shit! Don't go in the water

Animals in the Cnidaria phylum, have specialized stinging cells called cnidocytes, which you may already know. But you may not know that a jellyfish, or medusa, is just the most conspicuous life stage of this type of  animal. They begin as bottom-dwelling polyps and then develop into the open ocean killers you may know. They come in different sizes;
BIG...

and small...

Either way, thanks National Geographic, for making me scared to visit a beach ever again.