Fig. 2.

Colonies, skeletal cross sections, and microscopic images of the skeleton structure of four coral species. Dashed lines indicate the approximate cut orientation used to produce the sections. The cross-sections clearly show green colouration of the skeleton, indicating the presence of endolithic chlorophyll-containing phototrophs, and some skeletons show additional grey and orange regions indicative of other endolithic microbiota. The detail images of the skeletal structure illustrate that the two massive species illustrated (a and c) have large pores defined by the corallite structure, while Isopora palifera (b) and Porites cylindrica (d) have much smaller pore sizes and denser skeletons