Turritopsis dohrnii is the size of a pinky nail. When it's starving, injured or old, it melts into a blob and regrows as a juvenile polyp - then does it all again, potentially forever.
The biologically immortal jellyfish: how a 4.5mm medusa can revert to its polyp stage through cellular reprogramming.
Real Science breaks down transdifferentiation - the process that lets damaged cells rewind into a younger form.
The Natural History Museum tells how students in the 1980s left Turritopsis polyps in a dish and watched adults turn young again.
TED-Ed on why jellyfish - older than dinosaurs, brainless and boneless - are among evolution's great survivors.
Marine scientists at Spain's CSIC on what the jellyfish's enhanced DNA repair might reveal about aging.
A documentary on Shin Kubota, the eccentric Japanese scientist who has devoted his life to studying this animal.
The Natural History Museum weighs the limits of 'immortality' - predators, disease, and why the jellyfish can still die.