The longest-living organisms of all time Over hundreds of years, various species of living organisms have managed to survive for record-breaking periods—lifespans that might be unimaginable to the human mind—thanks to their unique traits and ability to adapt to harsh conditions. These creatures have withstood countless natural disasters, climate changes, and human interventions. Their astonishing longevity provides a glimpse into the past and helps us better understand our present environment. Here are some of the oldest living organisms that have survived for centuries and continue to exist today! The longest-living organisms on Earth! The immortal jellyfish The Turritopsis dohrnii , or the immortal jellyfish , is a small jellyfish believed to be the only species on Earth with the ability to revert to its juvenile stage when stressed or injured. This process allows this organism to live forever. Yes, you read that correctly! There may be jellyfish swimming in the ocean today...