The sexual (gametophyte) plant is delicate, up to 30 cm tall, with barbed branches and is rosy pink, yellowish-pink or whitish-pink in colour. The thallus has prominent major axes, bare in lower parts but densely tufted above. The plant is attached to other algae by barbed rhizoids. The asexual (tetrasporophyte) plant is a rose-pink in colour, and is formed of irregularly-branched, polysiphonous axes that are usually aggregated into spherical or hemispherical masses 1-3 cm in diameter.The asexual (tetrasporangial) phase of Asparagopsis armata
was once described as a separate species, Falkenbergia rufolanosa
. The alga is a non-native species first recorded in Ireland in Galway Bay in 1939 and Britain in 1949 at Lundy in the Bristol Channel.