@ShaulaEvans The jellyfish Turritopsis dohrnii can reverse its aging process.
The animal that lives forever | BBC Earth
The so-called ‘immortal’ jellyfish, or Turritopsis dohrnii, can somehow reprogramme the identity of its own cells, returning it to an earlier stage of life. In other words, it can age in reverse and morph from an adult back into a baby. The jellyfish has the ability to become a younger version of itself - a spectacular survival mechanism that plays out when it gets old or sick or faces danger.
(www.bbcearth.com)