Book 2 in the Children of Time series has a civilization of genetically modified octopuses. They have a sort of dual intelligence, with their more conscious mind handling big ideas and emotions while their arms host a distributed intelligence that handles stuff like math and problem solving, and the two function independently and are only somewhat aware of each other.

They are incredibly alien and yet so very relatable. It was weird listening to the description of how their minds work on two different levels at once and realizing that this was coming from an audiobook that I was using to keep one half of my brain occupied while the other half gets work done.