as the name indicates, Porpidia crustulata is a lichen that grows as a crust on rocks. It prefers silica rocks and is a pioneer in settling new areas. My finding is growing on a pebble from the Lech bank near Warth, Tirol, Austria.
a) Habitus-foto, 90 mm Macroobjective
Here and there the black apothecias are nearly circular ordered. This corresponds to the annual rings that are found at trees.
b) Stereomicroscope: The black apothecias show a thin border. The lichen itself forms only a thin, grayish and cracky layer on the stone.
c) Closer look at the apothecias, Stereomicroscope, ca. 60x
