A thin, encrusting lichen, mid to dark green, found on rocks of the lower intertidal zone. Apothecia are small and black, irregular and occasionally ridged. Easily confused with the commoner Verrucaria mucosa

Determiner: 
Rebecca Yahr

References: 
Smith et al. editors (2009) The Lichens of Great Britain and Ireland Dobson (2018) Lichens: an Illustrated Guide to the British and Irish Species