Coral patch reef, whichis 15 m in width and 20 m in thickness, is composed mainly ofcolonial rugose corals: (Lonsdaleia and Antheria), and Syringo-pora with crinoids filling around them. 
Longjiangdong biostromal reef is about28 m wide and 15 m thick, grows on crinoidal banks, and hasthree cyclical growth stages. Diphyphyllumis abundant and accessory organisms are crinoids, brachiopods,calcareous algae, and foraminifers (Fig. 5B). The coral patchreef at Longjiangdong is about 20 m wide and 8 m thick. Themain reef-builders are Thysanophyllum and Lithostrotionella(Petalaxis) (colonial rugose coral) with Caninia (solitary rugosecoral) secondarily incorporated. Thysanophylum and Lithostro-tionella successively occur in the reefs in clusters, and Caniniarandomly grows near the clusters. Reef-dwellers are mainlycrinoids. TheLongjiangdong reefs were formed at shallow SW platform margin, and grew and demised due to relative sea-levelrise and fall, resulting from the increasing micrites and sparrycalcite in the reefs and their overlying limestones, respectively