Fig. 2. Scanning electron micrograph of a typical fracture surface of the oral epithelium of a frozen-hydrated and superficially etched Galaxea fascicularis polyp prepared for selected area analyses. The external seawater layer (EXT), oral ectoderm (OE), mesogloea (Mg), oral gastrodermis (OG), zooxanthellae (Zx), mucus granules (M) and extrathecal coelenteron (ETC) are clearly distinguishable. Scale bar, 10 µm.