Evolution built advanced minds not once, but at least twice, gifting them not only to mammals and their kin, but also to cephalopods, and especially to the animal at the apex of ocean intelligence: the octopus. These are animals so unlike us that most aliens we imagine in our fantasies about outer space have more in common with humans. But there is no denying their sentience. I believe the first aliens we encounter will rise to greet us from the sea.