Tar Lichen

Verrucaria maura is a lichen that forms a thin, matt-black layer on rock surfaces that can resemble an oil stain. Reproductive bodies may be present as tiny black spots. Under magnification the surface is seen to be covered with a mesh of fine cracks that resemble dried mud.

Thallus extensive, black, cracked-areolate, matt and minutely dotted; perithecia up to half-projecting above the surfaces of the areoles, conical. Often dominant on coastal rocks, forming a zone at and above the high water mark.