Are jellyfish immortal?

The immortal jellyfish Turritopsis dohrnii may be able to turn back its lifecycle. It may not be able to avoid the inevitable slowing down who it comes to their age. Scientists have discovered that a jellyfish can live forever and the Turritopsis dornii is known as the immortal jellyfish. These creatures do not die.

They are transformed back into juvenile polyp state. Their tentacles retract, their bodies shink, and they sink to the ocean floor and start the cycle all over again. The only way they die is if another fish consumes them or if disease strikes the jelly. This jellyfish revert to a sexually immature stage.