A. Illustration of diatoms, cyanobacteria and minerals by differential interference contrast microscopy. B. Spirulina sp., Lyngbya sp. and divers micro-organisms by confocal laser scanning microscopy. C. Illustration Spirulina sp. and undetermined filaments by confocal. D–H. SEM images of golden-coated samples of: (D) Carbonates composed of nanospheres (zoom on photo G) precipitated close to diatoms and filamentous cyanobacteria (white arrow): (E) Micro-peloids of carbonates formed close to diatoms; (F) Trigonal microfabric of carbonates; (G) Nanospheres of carbonates; (H) Cross-section of cut and polished coated bubble included in LR-White resin.