This book presents an overview of our current understanding of the biomineralization mechanisms for shell formation in the pearl oyster Pinctada fucata, based on molecular biology, biochemistry, cell biology, structural biology and environmental biology. Pinctada fucata is the major pearl-producing shellfish in the South China Sea and is also an established model system for the research on the nacre biomineralization mechanism. Extensive studies on nacre biomineralization have provided valuable information for novel bionic material design. Discussing the isolation and gene cloning of the matrix proteins involved in the shell formation, as well as the cell signaling pathways, shell microstructures, and the environmental impacts on shell biomineralization, it is a valuable reference resource for researchers working in the field of nacre biomineralization and biomaterials.