Thallus pale, inconspicuous or immersed in the rock surface; apothecia with distinct, black margins but with discs usually densely blue-grey pruinose, chestnut-brown to black under the pruina. 

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Widespread on limestone and other calcareous rocks, mortar and similar substrates.

All year round.

Widespread and fairly frequent in Britain.

Status in Leicestershire and Rutland not known.