Immortal Jelly is Immortal
So, I recently found out about a rare colony of freshwater medusa floating around my buddy's cabin and it totally reminded me of this nifty little creature that I found out about awhile back. Allow me to introduce you to the turritopsis nutricula more commonly known as the immortal jellyfish.
You read that right. This little guy is immortal. How did lilltle 'cula pull it off? Simply put, instead of dying, it just turns back into a baby. More complexly, this little guy is a master of transdifferentiation, where the cells of one type can change into another. This is the same strategy some lizards use to regenerate tails. 'cula can do it with all the cells in it's body. So instead of dying it reverts to its immature polyp stage and just keeps on trucking. Theoretically, this little jelly can flip between these two stages indefinately. Unfortunately, nobody has ever complete a study to prove it...