When we think of immortality, it usually belongs to the world of myths or science fiction. But surprisingly, Earth is home to creatures that seem to defy ageing. The most famous is the immortal jellyfish (Turritopsis dohrnii). This tiny sea creature has the extraordinary ability to reset its biological clock. When it faces stress or old age, it transforms its adult cells back into a youthful state, essentially starting life all over again.

Scientists call this process transdifferentiation, and while it doesn’t guarantee invincibility against predators or disease, it makes the jellyfish biologically immortal. Alongside this marvel, other long-living species also inspire wonder. For example, Greenland sharks can live for over 400 years, making them the oldest known vertebrates. Similarly, giant tortoises and bowhead whales have lifespans that stretch across centuries.

These animals raise big questions about ageing and survival. While humans continue to chase the dream of longevity, nature quietly holds the secrets within its oceans and forests.