How would you like to have fossilized jellyfish on your bathroom floor? They could have ended up as tile ornaments (or maybe in our electric power plants, feh) had the scientists not found them first in a quarry in Wisconsin. Jellyfish have no durable body parts, and thus they don't really make good fossils, which is why finding this particular load from 510 million years back is like finding gold in your bathroom, or backyard.