Researchers from the Weymouth Sea Life Centre are providing octopuses with Rubik's cubes to determine whether the animals prefer one tentacle over another, or another, or another, etc. I bet they secretly hope that one of the animals will solve the puzzle. From Nature's The Great Beyond:
“Uniquely, octopuses have more than half their nerves in their arms and have been shown to partially think with their arms,” says Claire Little, of the Weymouth Sea Life Centre. “Many animals have been shown to favour a certain arm so we will see if octopuses can be added to that list.”Octupus and Rubik's Cube (Nature)
According to Little, the findings could help make life in captivity more pleasant for these intelligent, (and occasionally shark eating), animals. “They are very susceptible to stress, so if they do have a favourite side to be fed on, it could reduce risk to them,” she says.