Turritopsis dohrnii is a species of jellyfish the size of your pinky nail. It’s been found off the coast of Japan, Panama, Italy, Spain, and Florida. And some researchers say it can live forever. In a process called transdifferentiation, these jellyfish can transform dying adult cells into new healthy cells, effectively regenerating their entire body and then continuing their lifecycle. Only a handful of scientists study how turritopsis dohrnii does this, since the species is difficult to capture and keep in a lab. Their research may offer insights into treating neurodegenerative diseases—like Parkinson’s—by replacing lost or damaged neurons in the brain. Learn more by watching this video, and explore the enduring world of lobsters, hydra, and humans looking to live forever in our members-only field guide on Immortality.