Fourty thin sections were prepared for the study of the shell wall microstructure of the molluscan shells were collected from Abhor, Jeddah, Kingdom Saudi Arabia. The studied shells comprise: Arca imbricate, Anadara (Anadara) antiquate, Tellina rugosa, Spondylus (Spondylus) gaederopus Tridacna gigas, Chama pacifica, Cardites antiquate, Dosonia (Dosonia) radiate, Barbatia barbata, Turbo argyrostomus, Nerita polita, Cerithium ruppelli, Strombus gibberulus, Strombus fasciatus, Bursa granularis, Cypraea staphylae, Conus virgo, Nassarius arcularis, and Terebra nebulosa.The detailed microscopic examination has revealed many observations of shell wall microstructures.