As associate professor Maria Pia Miglietta, a marine biologist at A&M University in Texas, explains, Turritopsis dohrnii has an incredible ability to cheat death. "Turritopsis is unique, because when faced with unfavourable conditions and I mean high temperature, physical cutting, starvation, chemicals in the water, you name it " when you try to kill the jellyfish, it doesn't die." Most normal jellyfish start off life as larvae. They metamorphose into polyps (tiny, stationary soft bodies) that bud off swimming medusas, which grow up to become adult jellies. Eventually, after reproducing, most will stop swimming, crumble a little and then die. But the immortal jellyfish escapes that fate. It reverts to a juvenile form, and starts its life cycle again. The process is called "cellular transdifferentiation", Miglietta says. The jellyfish looks like it's dying and sinks to the bottom. Then " like a butterfly returning to a caterpillar " it shrinks into a ball, and within 24 to 48 hours, buds off a new polyp with the same identical genome, she says. It's one of "nature's coolest tricks", says ... Raquel López-Aragón. "When this jellyfish gets old or gets hurt, instead of just dying like most animals, it transforms itself back into a baby jellyfish and grows up all over again. It can do this as many times as it wants, which means theoretically it never has to die from getting old, it just keeps hitting the reset button on its life."