The internal part of most molluscan shells is made of mother-of-pearl which is secreted by the mantle. Because of its economically importance, particularly in perliculture, the structure and formation of nacre has long been studied by several authors (Gregoire, 1972; Wilbur et Saleuddin, 1983; Cuff, 1992). Lot of works lead on the specificity of an organic matrix secreted by the cells of the mantle which initiates the crystal nucleation (Erben and Watabe, 1974; Weiner and Traub, 1984; Belcher et al., 1996; Bowen and Tang, 1996). However, the biological mechanisms involved in biomineralization remain relatively unknown because of the difficulty to analyse the deposit of crystal.