More than 25 reefs in Saratov region.
reef area 100x200 km. 
Main reef builders are stromatoporoids: Paraamphipora, Stromatopora, Anostylostoma, Parallelopora.
Tabulate corals: Cyclochaetetes, Grassialviolites, Thamnopora
Rugosa: Dasphyllum, Neotrigophyllum, Thamnophyllum, Taneckiella
Algae
Algae and brachiopods, too.
Oil field