Leech of Yoh-Vombis

The Leeches of Yoh-Vombis were introduced in "The Vaults of Yoh-Vombis (fiction)" by Clark Ashton Smith.

Description

A sort of black cowl that covered the upper head and drooped down at the sides in wrinkled folds... when closelier studied, continued to baffle us. It was covered with a fine, mould-like pile, unclean and dusty as ancient cobwebs. Something about it, I know not what, was abhorrent and revolting.... Then... 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...
— Clark Ashton Smith, "The Vaults of Yoh-Vombis (fiction)"

A Leech of Yoh-Vombis is a parasitic creature native to Mars. In appearance it is a shapeless sluglike dark creature, like a flexible hood or flattened jellyfish. The creatures were introduced in "The Vaults of Yoh-Vombis (fiction)" by Clark Ashton Smith, where human archaeologists found the creatures entombed in a vault within a ancient Martian city. The organism can apparently glide through the air, envelope the head of a humanoid victim like a cowl, digest the skull and brain, and assume control over the body. The only know way to remove them is to aggressively attack them with a knife as soon as they attach themselves.

Associated Mythos Elements

• race: Martian (Yorhi) and Martian (Aihai)
• location: Mars, city of Yoh-Vombis

References

• fiction: "The Vaults of Yoh-Vombis (fiction)" by Clark Ashton Smith
• film: see Alien (1979) and its sequels, which were likely inspired by the story
• sourcebook: Malleus Monstrorum