>>5213713It works on flesh, it doesn't have to be brain although brain is probably better.
A space wolf has been described as thinking "the ponderous thoughts of trees" when he ate a piece of bark with the blood of a Tyranid monster on it. And of course he also determined the thoughts of the tyranid too.
Also yeah Orks do have brains. Ghazghuklls got pulped but miraculously healed, and also the feared "Squig Brain Transplant" is a thing among them.