Calling someone a 'sea floor skimming jelly fish' would make a great insult too - to wit: "You are about as smart as a sea floor skimming jellyfish."
This Jelly fish looks more like a "Sci-Fi" machine rather than a creature and it's uniqueness as an aquatic creature has inspired me to post it.
From National Geographic:
"..."This is a special kind [of trachymedusa jellyfish] which, instead of floating around in the middle of the ocean"—as most jellyfish do—"floats just centimeters above the bottom, with its tentacles touching the seafloor," team member Monty Priede said. "This is a very unusual thing." ..."