Yu Nao Shi

Yu Nao Shi (魚腦石), literally 'fish brain stone,' is the otolith — the calcium-carbonate ear bone — of the large yellow croaker, Larimichthys crocea (Richardson), and the small yellow croaker, Larimichthys polyactis (Bleeker) (Sciaenidae), marine fishes harvested along the coasts of eastern and southern China. The paired otoliths are recovered from the cranial cavity when the fish are processed for food, washed clean, and dried; the resulting smooth, hard, ivory-white stony bodies are 1–2 cm long with a characteristic groove. In TCM, Yu Nao Shi is classified as sweet and salty, neutral or cool, entering the Bladder and Kidney channels, and is used to promote urination, expel stones, clear heat, and detoxify, with classical and modern indications including urinary stones, painful urinary dysfunction, otitis media, and sinusitis (sometimes used topically as a powder). As an animal-derived material, plant fields do not apply.