Looking for the name of a story I read years ago. Astronauts I believe on an alien world, get attacked by alien brain parasites that I think take over their bodies. The parasites sit on the skull.
This sounds like The Vaults of Yoh-Vombis, by Clark Ashton Smith. Set on Mars. Some archaeologists investigate a dead Martian city. They're puzzled by the wall carvings showing Martians plucking at strange turbans they're wearing (which are actually the parasites). They continue exploring, and of course release the parasites.
The doorway beyond the shallow urn admitted us to a larger chamber, whose floor was comparatively free of dust. We found that the dark stone beneath our feet was marked off in multiform geometric patterns, traced with ochreous ore, amid which, as in Egyptian cartouches, hieroglyphics and highly formalized drawings were enclosed. We could make little from most of them; but the figures in many were doubtless designed to represent the Yorhis themselves. Like the Aihais, they were tall and angular, with great, bellows-like chests; and they were depicted as possessing a supplementary third arm, which issued from the bosom: a characteristic which, in vestigial form, sometimes occurs among the Aihais. The ears and nostrils, as far as we could judge, were not so huge and flaring as those of the modern Martians. All of these Yorhis were represented as being nude; but in one of the cartouches, done in a far hastier style than the others, we perceived two figures whose high, conical craniums were wrapped in what seemed to be a sort of turban, which they were about to remove or adjust. The artist seemed to have laid a peculiar emphasis on the odd gesture with which the sinuous, four-jointed fingers were plucking at these head-dresses; and the whole posture was unexplainably contorted.
Octave cried out in dismay, and then began to cough and sneeze, as the cloud of brown powder, floating with airy lightness, enveloped him. We others all stepped back to avoid the powder. Then, above the spreading cloud, I saw an unbelievable thing. The black cowl on the mummy's head began to curl and twitch upward at the corners, it writhed with a verminous motion, it fell from the withered cranium, seeming to fold and unfold convulsively in mid-air as it fell. Then it dropped on the bare head of Octave who, in his disconcertment at the crumbling of the mummy, had remained standing close to the wall. At that instant, in a start of profound terror, I remembered the thing that had inched itself from the shadows of Yoh-Vombis in the light of the twin moons, and had drawn back like a figment of slumber at my first waking movement.
Conquering my revulsion, and choking with the dust, I bent over him and tore the flaccid, oozing horror from his head. It came with unexpected ease, as if I had removed a limp rag: but I wish to God that I had let it remain. Beneath, there was no longer a human cranium, for all had been eaten away, even to the eyebrows, and the half-devoured brain was laid bare as I lifted the cowl-like object, I dropped the unnamable thing from fingers that had grown suddenly nerveless, and it turned over as it fell, revealing on the nether side many rows of pinkish suckers, arranged in circles about a pallid disk that was covered with nerve-like filaments, suggesting a sort of plexus.
While most of the party is eliminated, the creatures are contained and the narrator leaves with his mind scrambled, but free of all but a dark compulsion.
It was then that the ultimate horror, the beginning madness, came upon me. Amid my crawling revulsion, my nausea-prompted desire to flee from that seething cavern-mouth, there rose an abhorrently conflicting impulse to return; to thread my backward way through all the catacombs, as the others had done; to go down where never men save they, the inconceivably doomed and accursed, had ever gone; to seek beneath that damnable compulsion a nether world that human thought can never picture. There was a black light, a soundless calling, in the vaults of my brain: the implanted summons of the Thing, like a permeating and sorcerous poison. It lured me to the subterranean door that was walled up by the dying people of Yoh-Vombis, to immure those hellish and immortal leeches, those dark parasites that engraft their own abominable life on the half-eaten brains of the dead. It called me to the depths beyond, where dwell the noisome, necromantic Ones, of whom the leeches, with all their powers of vampirism and diabolism, are but the merest minions . . . .