Scientists are studying certain animals that appear to be able to cheat death, including a jellyfish that can heal wounds quickly and other creatures that can survive extreme conditions. Some of these animals are also remarkably long-lived, with one species reportedly taking 150 years to reach sexual maturity and another able to live for 30 years without food. Researchers are working to uncover the secrets behind these animals' ability to survive and thrive in ways that seem to defy death.