Unless this lichen is fertile it is very difficult to locate. It grows over liverwort and moss leaves on trunks, branches and rocks in humid ravines and in woodlands as a translucent grey to greenish grey film. When fertile it’s unusual spherical to top shaped brown to brown-black fruits on a short furrowed stalk readily mark it out from other lichens. Under the microscope the very long thin spores (up to 200 microns long by 2 microns wide) and eight per ascus are also characteristic.
Photo: R G Woods