Turritopsis nutricula jellyfish
This species of jellyfish might be the only animal in the world to have truly discovered the fountain of youth. Since it is capable of cycling from a mature adult stage to an immature polyp stage and back again, there may be no natural limit to its life span. Because they are able to bypass death, the number of individuals is spiking. "We are looking at a worldwide silent invasion," says Dr. Maria Miglietta of the Smithsonian Tropical Marine Institute.