Fact
An octopus has three hearts and nine brains, sort of
Two thirds of its neurons are in its arms, and the arms can act without asking.
Octopuses have a central brain plus a large nerve cluster in each arm, so an arm can explore and grasp semi-independently. Two hearts pump blood through the gills, one through the body, and the blood is blue because it uses copper-based haemocyanin rather than iron. The body heart stops when they swim, which may be why they prefer crawling.