Octopuses are really incredible creatures. They diverged from humans in the evolutionary tree hundreds of millions of years ago. Our common ancestor would have been a very dumb animal. Their brain structure is so different: 8 semi-autonomous tentacles, with one sort of central coordinating body. What could it possibly be like to experience the world that way? They're probably the "peak" of intelligence with the most prominence, along with humans and intelligent swarming insects like bees and termites. I think it's really interesting. Is is it really possible to measure this kind of intelligence? Can we ever know just how smart they are?
And, of course, they're just interesting creatures regardless. Their bodies is flexible, yet strong, like one continuous muscle. Each tentacle has a slightly different "personality;" for a single octopus, some of its tentacles are more adventurous while others are more shy. They can change the color of their entire body, and do, for reasons we haven't figured out yet. They mate once, after which the female guards the egg cache without moving from the spot until she withers away.
Everything I read about them absolutely floors me. They're the closest thing we have to an intelligent alien species.