Description: Thallus is reddish-brown to almost black, tough, narrow, flattened to somewhat canaliculate, to 10 cm (4 in) tall, broadening distally into several dichotomous segments, which are usually covered with papillae. Like Turkish Washcloth, this species alternates with a diploid Tar Spot crust, which is usually nearby. Habitat: Growing in clusters on rock in the mid intertidal of semi-exposed and exposed habitats. Similar taxa: Mastocarpus pacificus is more flaccid and prefers less exposed habitats.