9. Red Sea Urchin
The red sea urchin is an unassuming creature with an extraordinary lifespan—some are believed to live over 200 years with very little sign of aging. Unlike many other echinoderms, red sea urchins maintain cellular function and tissue repair remarkably well even at great ages.
Researchers featured on ScienceDaily have found that their longevity is likely tied to efficient cellular maintenance. This places them among the most age-resistant animals in the ocean.