There's a type of jellyfish that's immortal - Apparently.
The Turritopsis dohrnii, also known as the "immortal jellyfish," is a species of jellyfish that can transform its body into a younger state through a process called transdifferentiation. This means that it can essentially revert back to its polyp stage, which is the juvenile form of a jellyfish, and then grow back into an adult again. This process can be repeated indefinitely, making the Turritopsis dohrnii theoretically immortal. This phenomenon was first discovered in 1993 by marine biologist Maria Pia Miglietta.