Fig. 4 in Nanostructure of biogenic versus abiogenic calcium carbonate crystals

Fig. 4. Calcareous sponge Petrobiona massiliana Vacelet and Lévi, 1958, Recent, Marseille, submarine cave, "Grotte du Figuier", depth 10 m; ZPAL V.31/3. Polished and etched (formic acid, 1%, 20s) basal skeleton (spherulites) with calcite fibers; two enlargements (A, B). AFM (contact mode; buffered pH = 8, ammonium persulfate 1%, 10 min.): height−2D projection (C, E), and deflection (D, F) images of 2×2 µm (C, D) and 500×500 nm (E, F) skeletal surface. Nanograins ca. 50–100 nm in diameter. Grayscale bars (left) show z−scale (height) of 2D projection images.