Tangential, but really, really good: What is it like to be an octopus? https://www.lrb.co.uk/the-paper/v39/n17/amia-srinivasan/the-...

An Octopus may seem more like an alien with its 9 brains (one central, plus one per tentacle), but note that the left/right hemispheres of other animal's brains are essentially separate brains, and human's who have had "split brain" surgery to separate these (e.g. in cases of severe epilepsy) don't report feeling much, if at all, different afterwards than they did before.

I would expect that an Octopus's central brain may well feel as if it is directly controlling it's arms, and receiving sensory feedback from them, even though it is not.

The reality is that we don't see the external world - we predict it (and receive error feedback), and similarly our brain can't also help but predict itself, whether its hemispheres are connected or not, and gets pretty good at both doing this as well as creating post-hoc rationalizations that feel like it's perfectly in control. I would assume that an Octopus's "main brain" is predicting what its tentacles are going to do in similar fashion, and would not feel that they have a mind of their own!

Strange coincidence, I just read a novel that explored what it is like to be a bat and what it is like to be an octopus.

https://en.wikipedia.org/wiki/The_Mountain_in_the_Sea