This is an off-white or bluish-grey cracked, crustose lichen. Apothecia are rare, but when seen they are tiny with dark steeply convex discs and narrow rims. One or two are found on the areoles.
Often found on rocks where seabirds perch in the splash zone, very rarely on exposed rocks inland. Common and widespread on rocky coasts.
Photographs of Aspicilia leprosescens, taken April 2012, Llandudno, Wales. © Pete Hillman 2012. Camera used Nikon Coolpix P500.