We know that the octopus is smart but the hardware “has little in common with the mammalian design”:
While the octopus has a large central brain in its head, it also has a unique network of smaller ‘brains’ within each of its arms. It’s just what these creatures need to coordinate the mind-boggling complexity of eight prehensile arms and hundreds of sensitive suckers, which provide the octopus with the equivalent of opposable thumbs (roboticists have been taking note)…
For instance, an octopus escaping a predator can detach an arm that will happily continue crawling around for up to 10 minutes.
Indeed, until an experiment by Kuba and colleagues in 2011, some suspected the arms’ movements were independent of their central brain. They aren’t. Rather it appears that the brain gives a high-level command that a staff of eight arms execute autonomously.
This from an animal related to oysters.
“The arm has some fascinating reflexes, but it doesn’t learn,” says Kuba, who studied these reflexes between 2009 and 2013 as part of a European Union project to design bio-inspired robots. Elizabeth Finkel, “How the octopus got its smarts” at Cosmos
Some think that a clue might lie in an oddity of the octopus’s genes. The octopus has a very large genome and can edit their own genomes,altering their RNA. They “ do not always follow their genetic instructions to the letter … More. (“Is the octopus a “second genesis of intelligence”?” at Mind Matters Today)
See also: Apes can be generous: Are they just like humans then? Michael Egnor: If we are to genuinely understand machines, animals, and ourselves, we need to clearly understand that it is the immateriality of human intellect and will—our capacity to think and act abstractly— that makes us radically (i.e. ontologically) different from any animal or machine.