Description: This lichen is by far the most common maritime lichen found on Alaska’s coast. The thallus forms extensive black patches that penetrate the surface of siliceous and limestone rocks. They often develop a chinky surface reminiscent of cracked dry mud, or produce low rounded bumps that protrude from the surface. Another species of Verrucaria often grows on top of V. maura. No reproductive features such as soridia or isidia are produced. Habitat: Hydropunctaria maura and other Verrucaria-like species form a striking black band on rock from the high intertidal zone into the supratidal. The lower edge of this band usually marks mean higher high water (MHHW) and the width of the band varies with exposure (less than 1 meter (39 in) wide in protected areas, and more than 5 meters (16 ft) wide at exposed locations). This lichen is often mistaken for weathered oil.