lion's mane jellyfish
HOAX: This photo of a lion's mane jelly fish "next to" a diver is photoshopped. The caption that usually goes with it has SOME true facts about the jelly, but allege that they get 18 fee or so across the bell. No, the largest gets about 7 feet. See another photo on this page of what a real size comparison looks like near a diver.