Margen
The octopus runs on a body plan that seems to come from another planet. It pumps its blood with three hearts: two push it towards the gills and the third sends it to the rest of the body. And that blood is bluish, because it uses copper instead of iron to carry oxygen.
The strangest part is its nervous system. Of its roughly five hundred million neurons, about two-thirds are not in its head but spread through its eight arms. Each arm can probe, grip and react with a good deal of autonomy, almost as if it had a mind of its own.
That's why an octopus can be prising open a shell with some arms while others explore a crevice. It isn't a body ruled by a single boss: it's more like a team of eight coordinating on the fly.