"Well, why would he have to be. A jellyfish is odd to us but not an alien. Researchers find new life frequently enough that it seems obvious that there are still lots of species that have never been discovered, that may never be. That there are many that had come about and then gone extinct. There may also be other types of life that don't fit the current definition, are not within the boundaries we have set, and so we don't see them at all and we...