A pale yellow-green leprose crust, arising from aggregations of separate granules, eventually forming a cracked crust. On rain-sheltered siliceous rocks, extending further into sheltered cavities than most other British lichens, and typically forming pure stands. See Orange (2020) Lichenologist 52: 425–435 for details. NB the map includes records of a similar species found in crevices in dry bark on older trees, which are not this taxon and mostly refer to Andreiomyces obtusaticus. These will be separated out at a later date..