2 · Nature
25 · earth, world as celestial body
25F · animals
25F7 · lower animals
25F72 · molluscs
25F72(...) · molluscs (with NAME)
25F72(MUSSEL) · molluscs: mussel
25F72(MUSSEL)(+9) · molluscs: mussel (+ products of animals)
25F72(MUSSEL)(+93) ·
molluscs: mussel (+ pearl ~ product of animal)