Other Minds, about cephalopods, is written by a philosopher, not a biologist or neuroscientist, so take it with a grain of salt[1]. I would also recommend _Octopus_ by Anderson, Mather, and Wood, who are actual biologists.
[1] Specifically, cephalopods are very intelligent compared to other invertebrates, but that's it. It's interesting because they represent a parallel evolution of greater intelligence outside the vertebrates, and because what they can do with that intelligence is greatly enhanced by their physical capabilities. Give a fish a human brain and it will have trouble twisting a lid open.
[1] Specifically, cephalopods are very intelligent compared to other invertebrates, but that's it. It's interesting because they represent a parallel evolution of greater intelligence outside the vertebrates, and because what they can do with that intelligence is greatly enhanced by their physical capabilities. Give a fish a human brain and it will have trouble twisting a lid open.