What is the longest-living animal on Earth?

The longest-living animal on Earth is the ocean quahog (Arctica islandica), a species of clam. Some specimens have been found to live over 500 years. These clams inhabit cold waters in the North Atlantic Ocean, where their slow metabolism contributes to their extraordinary lifespan. Another contender is the immortal jellyfish (Turritopsis dohrnii), which can revert its cells to an earlier stage of life under certain conditions, potentially avoiding death from old age. These creatures are fascinating examples of longevity in the natural world.