The World's Only Immortal Animal

The turritopsis nutricula species of Jellyfish has been discovered to be the first, and possibly only, immortal creature. Once the creature reaches its adult form (pictured) it can, apparently, use transdifferentiation to transform its cells backwards to the polyp stage of its life and begin the whole cycle again.

On the one hand, imagine living forever, on the other hand, imagine being a jellyfish? This creature might have seen dinosaurs, or Jesus walk on water, or the original Sugababes.