Description: Thallus is green, growing in tufts 2-15 cm (1-6 in) tall, composed of branched, interwoven, uniseriate filaments, ususally without hook-like branchlets or rhizoids. Cells to 150-200 μm diameter, sometimes shorter than broad, overall aspect is usually spreading, but the species occasionally forms dense, ropelike tangles. Habitat: This species is an annual found on rock in the low intertidal of semi-protected to semi-exposed habitats. Similar taxa: Acrosiphonia spp.