The biologically immortal jellyfish. Perhaps the closest example of immortality man will see. This jellyfish can revert to its polyp stage after becoming sexually mature. It originated in the Caribbean, but has spread all over the world.
Person 1: What's ur favorite animal, man?
Person 2: The TURRITOPSIS NUTRICULA!!!!
*waves arms like a jellyfish and smacks friend in the face to simulate stinging*