Antithamnion pacificum, Antithamnion alternans, Antithamnion asymmetricum, Antithamnion uncinatum, Callithamnion floccosum var. pacificum, Irtugovia pacifica

Description: Thallus is a delicate, uniseriate filament, reaching 15 cm (6 in) tall. Microscopic branches are opposite, usually short and unbranched, with squarish basal cells. The branch tip is somewhat sinusoidal. Habitat: This ephemeral seaweed grows on rock and epiphytically in the low intertidal and subtidal of semi-protected to exposed habitats. Similar taxa: Polysiphonia pacifica, Savoiea spp.,Antithamnionella floccosa