It has been discovered that Turritopsis nutricul, a jellyfish, is potentially immortal. Once the jellyfish sexually matures it looks like a 5mm parachute. If it runs into tough times the jellyfish can reverse metamorphose to the polyp it was in its youth until things get better and then transform back into its mature state. The jellyfish is the only known animal that can transdifferentiate or tranform the cells of its entire body. Theoretically this tranformation can be done indefinately essentially making the jellyfish immortal.