Do you ever wish you could turn back into a baby and restart your life all over again? Turritopsis dohrnii, commonly known as the immortal jellyfish, can revert from its adult form to an earlier stage of life when faced with extreme stress, injury or starvation — effectively restarting its life cycle.

Marine biologist Maria Pia Miglietta, an associate professor at Texas A&M University, says the species can survive conditions that would normally kill a jellyfish, including high temperatures, physical injury, starvation and chemical exposure.

“When you try to kill the jellyfish, it doesn’t die,” Miglietta said.

Most jellyfish begin life as larvae before developing into stationary organisms called polyps. These polyps eventually produce swimming medusas, which mature into adult jellyfish. After reproducing, they generally die.

Turritopsis dohrnii, however, can take a different route.

When stressed or injured, the adult jellyfish sinks, shrinks into a ball-like form and undergoes a biological process known as cellular transdifferentiation. Within roughly 24 to 48 hours, it can develop into a new polyp carrying the same genetic material.

In other words, the jellyfish effectively returns to an earlier stage of its life before growing up again.

Researchers studying the species in laboratories say this process means it could theoretically avoid dying from old age. But that does not make it completely immune to death — predators can still eat it.

Only one of the eight currently recognised Turritopsis species is known to possess this remarkable ability.

The jellyfish is tiny, measuring only a few millimetres, but it has been found across wide areas of the world’s oceans, including the Mediterranean, Atlantic waters and around Japan, Panama and Brazil.

Scientists are particularly interested in the species because its ability to reverse its biological development could offer clues about how cells change their identity and how ageing works.

For marine biologist Lisa-ann Gershwin, the creature’s significance goes beyond science.

Humans have dreamed of living forever for centuries, she says. The fact that a tiny jellyfish may have evolved its own version of biological rejuvenation makes the creature all the more fascinating.

For Turritopsis dohrnii, ageing does not necessarily mean the end. Sometimes, it simply means starting over.