Porpidiaceae Clauzadea immersa Growth type crustose Chemical reactions negative. Hymenium I+ pale blue Found on hard, well-lit or shaded calcareous rocks, walls, limestone pavements and ledges and also on church memorials White to pale-grey thallus, the deeply immersed blackish-brown apothecia often with pale-grey pruina. Pits left when apothecia fall out. Spores simple, 10-15(-19) × (6-)7-8(-9) µm, warted when mature. Pycnidia frequent. Microscope photograph below.

Microscope photograph

Clauzadea immersa
Corfe Mullen and Portland, Dorset. January 2014, February 2016