Figure 5

SEM images of CaCO3 products obtained from overgrowth experiments. (A) Control experiment, i.e., overgrowth experiment in the absence of soluble fraction of the skeletal OM. (B) Overgrowth experiment in the presence of 13.3 µg/mL of SOM extracted from O. patagonica. (C) overgrowth experiment in the presence of 33.3 µg/mL SOM extracted from S. pistillata. The insets show details of the overgrowth of CaCO3. The Miller index of the crystalline faces is reported. (D) Optical microscope image of an overgrown disc-like mineral on the surface of a calcite seed. (E) Raman spectrum collected at the point indicated by the green cross in (D), the vibrational absorption bands observed indicate only the presence of calcite.