Also called ‘Black-eyed Lichen’, it is a crustose, warty lichen, pale grey in colour with distinctive disc-like black fruiting bodies, each with a raised, pale grey rim. Thallus 10cm in diameter. Fruiting body 3mm wide.
Found well-lit coastal rocks in the splash zone, on seabird perches such as cliffs, and stone walls inland. Rarely found on trees. Common and widespread throughout the British Isles.
Photograph of Black Shields (Tephromela atra), taken June 2012 on sea wall, Llandudno, Wales. © Pete Hillman 2012. Camera used Nikon Coolpix P500