Fire Jellyfish Swarm

While individually one of these fist-sized jellyfish is merely a nuisance, in great numbers, fire jellyfish can form into dangerous swarms. Bobbing in the water, they create a cloud of stinging tentacles. They were named in part for their bright coloration, but those who are stung by fire jellyfish learn the larger reason for their name—the pain of their stings is comparable to being burned alive.

Many varieties of jellyfish drift through the world's oceans, feeding on fish and other tiny marine creatures. However, deadly species of monstrous jellyfish pose a threat to unwary swimmers and sailors alike. Note that while jellyfish are animals, they also have the mindless trait because they lack a centralized nervous system.