Turritopsis nutricula is a small hydrozoan that once reaching adulthood, can transfer its cells back to childhood.

T. nutricula is the first known metazoan that has been observed to sexually mature and return to its juvenile colonial stage.

This regression from medusa to polyp has only been observed with the presence of differentiated cells from the outer umbrella and part of the animals digestion system.

[7] Due to this regular transformation by T. nutricula, it is thought to have an indefinite lifespan.

[6] There are four stages that were found to describe the inverted life cycle of the Turritopsis nutricula: healthy medusa (where the T.nutricula would swim actively), unhealthy medusa (the T. nutricula was not able to swim), four-leaf clover, and cyst (would produce the polyp morphologically).