With a cap that is 200 cm across and tentacles that can reach more than three meters, the lion's mane jellyfish is among the largest jellies on the planet. Their eight bundles of upwards of 100 stinging tentacles each (which retain their sting even if broken off into fragments), also make this jelly a true nuisance.

Of course, for our purposes, it also looks like a floating clump of viscera. In fact, I wouldn't be surprised if my omentum, or even most of my abdominal cavity, looks like a lion's mane jellyfish, sans stinging tentacles.

Photo source: Phil Hartell
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