This slug like parasite is actually a symbiote. After attaching itself to a warmblooded host, it feeds off that being. However, its tenticles, growing under the skin, act as secondary nerves, increase the victims nerve responses.
Found written on a torn single page…
“Lay thee patiently and still upon the ground, contemplating the Leper Star in the firmament, 'neath a crescent moon, ‘midst the graves of a boneyard 'til the G’na-Shennu come crawling up from the foetid earth. Fear them not. Let them rage about thee, casting ghoul-dust from their chalky talons and scalps,'til they calm, and so begin to whisper their secrets. Then shall they solemnly withdraw into the earth once more, in peace."