The original illustration of the ustilagor. Note lack of facial features, but what fun is a crawling brain without eyes and an orifice? It also had limbs with which to scurry across a dungeon floor, but I decided that, if I did try to provide it with limbs, they would probably be damaged during the firing process.
Later editions of D&D reimagined the ustilagor as a larval form of the intellect devourer, a dog-sized human brain on four legs which, yes, did its best to make you stupider.
