Description: Thallus is reddish brown to almost black, tough, narrow, flattened, to 10 cm (4 in) tall, sometimes flaring into a blade at the distal end, which is usually covered with papillae. Like Turkish Washcloth, this species alternates with a diploid Tar Spot crust. Habitat: Growing in clusters on rock in the mid intertidal of semi-exposed and exposed habitats. Similar taxa: Mastocarpus spp.