Do octopuses have a favorite tentacle? asks the Independent.
Claire Little, a marine expert at the Weymouth Sea Life Centre, explained: "Uniquely, octopuses have more than half their nerves in their arms and have been shown to partially think with their arms. "
I remember something like that from Blindsight. I'm pretty sure mammals partly think with their limbs too, but unless we unfortunately stumble into some Futurama-Disembodied-Head scenario, we probably won't be able to show it to any great extent.
The paper says, "Octopuses belong to the same family as slugs and snails, but scientists believe they are far more intelligent than their relatives." This is slander, of course, as they are in the Class Cephalopoda, and the slugs and snails are in their own Class, the Gastropoda. (Classes contain Orders, which contain Families, which contain Genuses, which contain Species.) They are all in the same Phylum, Mollusca, and subphylum, Conchifera (Shell Bearers), but still.
As a comparison, all mammals are in the same Class, so humans and naked mole rats are phylogenetically closer than slugs and octopuses. (We're in the Phylum Chordata, Subphylum Vertebrata, in case you're wondering.)
Anyway, the important thing is the octopuses have been given Rubik's Cubes to play with.