Immortal Jellyfish (Turritopsis dohrnii)

Immortal Jellyfish (Turritopsis dohrnii) is one of nature's most extraordinary creatures, capable of biologically reversing its aging process. When stressed or injured, this tiny, translucent jellyfish can revert from its adult form back to a polyp stage—essentially resetting its life cycle indefinitely. Native to the Mediterranean and Japanese waters, its unique cellular regeneration defies conventional mortality, making it the only known "biologically immortal" animal. While predators and disease can still end its life, Turritopsis dohrnii challenges our understanding of aging, offering potential insights for medical science. A marvel of evolution, it truly earns its place among Earth's longest-living species.