Here Is A Great Idea,

when you get old you revert to your younger self, 

in other words immortality! and there is one creature on earth that does just that, it lives forever, photograph Bachware/Wikimedia Commons, Turritopsis dohrnii, a small species of jellyfish native to the Mediterranean, is commonly known as the "immortal jellyfish", and it literally lives up to its name, possessing the ability to revert to its a sexually immature stage instead of succumbing to an inevitable death, this tiny creature holds the secret to true biological immortality,

instead of dying like every other creature, the tiny immortal jellyfish first retracts its tentacles, turning into a blob, and then drops to the ocean floor and reverts to its polyp stage within three days. Scientists found that the new polyp is genetically identical to the original jellyfish, but it’s a juvenile version of it. Think of it as a chicken reverting to an egg, or a moth to a caterpillar,

forgetting the title song introduction here is a slightly longer look at the jellyfish, interestingly, the immortal jellyfish cannot completely control their reversal from medusa to polyp stage. Research has shown that the transformation only occurs when the jellyfish is injured or starving, or when the temperature or salinity of the water it lives in changes. However, if the conditions are right, it can potentially repeat the cycle indefinitely, there are three types of Turritopsis jellyfish in the world, the dohrnii, the nutricula and the rubra, but only the first carries the name of “immortal jellyfish”. It’s not that the other two are known not to be capable of the same remarkable transformation, just that dohrnii is the only one whose immortality has been proven in controlled, laboratory conditions, for the scientific rundown have a look here, so live like  human and die, or live forever as a jellyfish? a your choice!