DESCRIPTION: Crustose. This substrate hugging rosette-forming species reaches up to 10cm across and has a thallus that is grey-green to yellow-grey with small inner lobes that are incised or crenate and larger around the edge.  The apothecia are up to 2mm wide, are of a creamy-brown colour with a lighter margin. DISTRIBUTION: Common through the British Isle although less frequent in the north and west of Scotland. HABITAT: A very common species that has a liking for man-made substrates - e.g. bare cement, paving stones and asphalt. it can also be found below where birds roost and perch.