Photomicrograph from a boulder brain coral (Colpophyllia natans) found diseased in Biscayne Bay, Florida

Photomicrograph from a boulder brain coral (Colpophyllia natans) found diseased in Biscayne Bay, FL, US. There is lytic necrosis of the gastrodermis extending through the surface body wall (asterisk), and mucocyte hyperplasia with loss of gastrodermis from surface and basal body walls (black arrowheads. Surface epithelium (E), Gastrodermis of surface body wall (G), Basal body wall (B). Mesoglea (white arrowhead). Gastrovascular space (GVS), Corallite skeletal space (C), Seawater (S). H&E stain.