User blog comment:YoungOtakuNerd/The Not-So-Ultimate Life Form/@comment-3190872-20120803154122/@comment-32788838-20120803184745

There's a species of jellyfish which is theoretically immortal and also some bacteria species that are naturally immortal. They don't seem much like "ultimate life forms" to me. Also, Shadow isn't truly "immortal" either, just ageless really. He CAN die, its just he doesn't age like normal people.