Fig. (4) Thin sections of (A) Caloplaca flavescens on Vicenza stone, (B) Diploschistes euganeus on shingle, (C) Lecidea fuscoatra on shingle, (D) Dirina massiliensis on biocalcarenite. Calcium oxalates are deposited only on the surface (A); in the whole thallus (B); in the thallus and in the substrate, along the hyphal bundles (C). (E) SEM photograph of calcium oxalate (weddellite) deposited outside fungal hyphae (bar = 10µm).