Illustration of the main microbial structures and carbonate precipitates in Sainte Marguerite area. A. Microbial communities developed close to the spring in a reservoir. B. Microbial mats and filamentous cyanobacteria forming a biofilm of extracellular polymeric substances (EPS). C. Aragonite bubbles and associated microbial mats. D. Detail of the mineralization on blade of grass and aragonite preserved bubbles. E. Aragonite mineralization at the surface of a bubble. F. Aragonite raft at the air-water interface along the stream. G. Detail of the growing phase resulting from the mineralization in the carbonate system with erect fibrous micritic threads (15–20 μm) separated by micritic films.