Gu (Chinese: 蛊) or jincan (Chinese: 金蠶) was a venom-based poison associated with cultures of south China, particularly Nanyue. The traditional preparation of gu poison involved sealing several venomous creatures (e.g., centipede, snake, scorpion) inside a closed container, where they devoured one another and allegedly concentrated their toxins into a single survivor, whose body would be fed upon by larvae until consumed. The last surviving larva held the complex poison. Gu was used in black magic practices such as manipulating sexual partners, creating malignant diseases, and causing death. According to Chinese folklore, a gu spirit could transform into various animals, typically a worm, caterpillar, snake, frog, dog, or pig.