Did you know that this jellyfish can come back to childhood?

A small adult jellyfish swims in water. In the usual life cycle, this step seems to lead in only one direction. Turritopsis dohrnii has another possibility: under certain conditions, especially stress, it can return to a polyp stage.

The body is transformed. Cells change function and a fixed organism can again give birth to jellyfish. This reversal earned the animal an irresistible nickname: the “immortal” jellyfish.

The nickname, however, tells more than the observations. A predator can eat it; a disease can kill it. We have not found an indestructible being. Something more specific, and perhaps more disturbing, has been discovered: in this animal, becoming an adult does not permanently close the door on childhood.