Octopus brains are substantially different from mammalian, reptile, or even bird brains, having more innervation in its arms than its head, and no need for a brain-body map like we have -- and yet octopuses not only display intelligence, but social behavior that's recognizable to us as affection or hostility. An octopus will nuzzle the hand of a familiar, well-liked human with its tentacles, or squirt water at a despised human from its tank. If deep-sea creatures are the closest we've seen to aliens, then the behavior of octopuses suggests we may be able to establish social common ground with intelligent extraterrestrials should we ever encounter them.