Scientists have unlocked the genetic code of the immortal jellyfish in the hope of unearthing the secret to their unique longevity, and find new clues to human ageing.
The creature is capable of repeatedly reverting to a juvenile state and researchers in Spain have discovered the genes that could explain their long lives.
Scientists at the Proceedings of the National Academy of Sciences and University of Oviedo mapped the genetic sequence of the so-called immortal jellyfish species - Turritopsis dohrnii.
The species goes through a two-part life cycle and lives on the sea floor and has two copies of the genes that protect and repair DNA.

"We've known about this species being able to do a little evolutionary trickery for maybe 15-20 years," said Monty Graham, a jellyfish expert and director of the Florida Institute of Oceanography, who was not involved in the research.
This trick earned the species its nickname as the immortal jellyfish.
The study was aimed at understanding what made this jellyfish different by comparing the genetic sequence of T. dohrnii to that of Turritopsis rubra, a close genetic cousin that lacks the ability to rejuvenate after sexual reproduction.
What they found is that T. dohrnii has variations in its genome that may make it better at copying and repairing DNA.
Mr Graham added: "We can't look at it as, hey, we are going to harvest these jellyfish and turn it into a skin cream.
"It has more to do with understanding the processes and protein functionality that helps these jellyfish cheat death.
"It's one of those papers that I do think will open up a door to a new line of study that's worth pursuing."