THE IMMORTAL JELLYFISH

We're not really talking about Wolverine. It's all about a jellysifh  called Turritopses nutricula  that simply will never die by natural causes. Its regeneration capacity is so powerful tha it would only pass away if it was completely mangled.

This immortal jellyfish was first discovered by accident by the german marine biology student Christian Sommer, in 1998.

The regular jellyfishs' life expectancy is about hours or months and, extremely rarely, years. How can the immortal jellyfish cheat this system?

Turritopsis dohrnii - The Immortal Jellyfish

Sommer realized the jellyfish simply refused to die, regressing to its initial stage of development until restart its life cycle again, successively, like it had been suffered a reverse aging.

We don't need to worry about an immortal jellyfish invasion that will reproduce like crazy and populate the seven seas -  they are far from invincible. In the polyp stage they are very vulnerable and there are a lot of predators. Nevertheless they are still the only animals on the planet who can return to their immature stage and "begin your journey" again.

Resources:  http://www.hypeness.com.br/2013/02/essa-agua-viva-e-o-unico-animal-imortal-do-planeta/
http://hypescience.com/27905-o-unico-animal-imortal-da-terra/