Fig. 4.

Evidence for a boring mechanism based on transcellular Ca²⁺ transport. (A) LSCM calcium mapping of a heavily infested chip taken along the main boring direction shows supersaturation at the boundary layer (particularly in the heavily eroded surface) and within the boreholes close to the surface, and undersaturation around the deeper parts of the boreholes. (B) Quantitative data for Ca²⁺ concentration along the boreholes of single filaments measured in lightly bored chips (solid line is the average of 10 filaments; SDs shown as dashed lines); the dotted vertical line marks expected calcite-saturation equilibrium.