The immortal jellyfish

Turritopsis nutricula (now more accurately called Turritopsis dohrnii) is remarkable because it is considered biologically immortal. Its unique traits include:

1. Ability to revert back to a juvenile stage after reaching sexual maturity through a process called transdifferentiation

2. Can transform its existing cells into different cell types

3. Can repeat this cycle of aging and rejuvenation indefinitely

4. Only known animal capable of reverting completely to a sexually immature stage after having reached sexual maturity

When stressed or injured, it can transform its mature body back into a polyp (early life stage), essentially "aging backward." This process can theoretically continue forever, making it potentially immortal in the absence of predation or disease.

Would you like me to elaborate on any of these aspects of its unique biological capabilities? known until the mid-1990s.