Most fascinating alien consciousness explored in SF
The Arikei in Embassytown by China Mieville follow linguistic determinism. For them, words are physical states and not symbolic abstraction like it is for humans. Their words are directly linked to their reality. As human language is perceived to be disconnected from their immediate physical reality, they can’t comprehend humans directly.
The octopuses from Children of Ruin by Adrian Tchaikovsky have mini-brains across their bodies. They communicate through a shifting array of pigments and textures on their skin.
The ocean from Solaris by Stanislaw Lem touches at the dangers of trying to understand “god-like” consciousness. The entire project of trying to decipher any pattern or meaning behind the actions of the ocean falls flat as it is simply too beyond our understanding.
Stevland from Semiosis by Sue Burke experiences reality through root networks, nutrients, and evolutionary strategies. All animals and humans to him are a passing phenomenon that he humours and tends to.