The thallus is frequently immersed in the substrate. If not it appears off white to light brown. Usually smooth to slightly granular but it may also show cracking that starts at the oldest and thickest part. It is usually dotted with large and flat-topped black spheres.

Found on soft calcareous rock and mortar, especially on old walls.

All year round

Widespread and fairly frequent in Britain.

Fairly frequent in Leicestershire and Rutland.