Gomphillus calycioides

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