Immortal Jellyfish

Slightly late for Easter: here is the path to eternal life! The path involves being a jellyfish of the species Turritopsis nutricula. Jellyfish have a fascinating life cycle: before they live in their familiar shape (called their "medusa" stage), they live as stationary polyps. Polyps bud off multiple medusae, or sometimes other polyps. The medusae will generally reproduce and then die, but in Turritopsis nutricula a medusa can actually revert back to its polyp stage. Theoretically, an individual organism could repeatedly mature and back-mature and thus go on forever: hence, eternal life.

In practice, you're talking about avoiding only death by natural causes, and jellyfish tend to get killed or eaten. But even so: polyps will bud off a number of genetically identical medusae, any of which might conceivably back-mature into polyps again, then bud off more medusae, and so on. So in a sense, you've got some opportunity as a Turritopsis nutricula for a part of you to keep going.

Now, who are "you" if you're a number of disconnected and not-very-sentient medusae that budded from genetically identical polyps? Probably not much. But that's the price you pay for immortality.