Verrucaria muralis

White to greenish-white thallus, immersed, smooth or cracked. Black perithecia are immersed or prominent, leaving shallow pits in substrate.

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.

Found on bricks, mortar, soft limestone rocks and pebbles and on shells.

All year round.

Widespread and common in Britain.

Status in Leicestershire and Rutland not known.