Essential component of the organic matrix for normal growth of the nacreous layer. The complex contributes to the initiation of aragonite crystallization as well as subsequenct stacking of aragonite tablets in the nacreous layer (By similarity). Pif80 binds to both aragonite and calcite crystals, with a higher specificity for aragonite crystals. Pif97 contains a chitin-binding domain that allows for attachment of the entire complex to the chitin-containing organic framework. Heterooligomer; disulfide-linked. Pif97, Pif80, N16 and other proteins form a complex (By similarity). Nacreous layer of shell (at protein level). Expressed primarily in the mantle with highest level in the mantle pallium and lower level in the mantle edge. Pif80 and Pif97 are rich in Asp. This amino-acid appears to be common to biomineral-forming organisms (By similarity).