Caloplaca microthallina, so called because of the very small areoles, which can just about be seen in this photo.It usually grows on the black lichen, Verrucaria maura, as here on which it is apparently parasitic. It is a common species usually found close to the upper tide limit on acid rocks. This photograph was taken in St Brelade's Bay, Jersey. This completes those Caloplaca species most likely to be found close to or associated with the coast.