Turritopsis nutricula is a type of jellyfish, just big enough to see with your naked eye, and it’s considered by scientists to be an animal that cheated death.
Turritopsis nutricula managed to find a way to beat that. What these little folks do is they revert completely to a sexually immature, colonial stage after they reach sexual maturity. They’re even cooler than that. When they’re young they’ve got only several tentacles, but at a mature stage, they get to 80-90 of them. They’re able to return to polyp stage due to a cell change in the external screen (Exumbrella), which allows them to bypass death. As far as scientists have been able to find out, this change renders the hydrozoa virtually immortal.
to read more about them: Turritopsis nutricula in Wikipedia