Sphaerococcus coronopifolius Stackhouse
Also known as Hematocelis fissurata Crouan frat.
Description: Narrow, compressed, two-edged, cartilaginous, scarlet fronds, main axes dark brownish-red, to 300 mm long. Branching abundant, distichous, subdichotomous or alternate, terminal branchlets acute, fringed with short marginal proliferations. Tetrasporophyte is Haematocelis fissurata, a thick crust with oily fissures, with which it is sometimes found.
Similar species: Plocamium cartilagineum.
Habitat: On rock, subtidal to 20 m., southern and western shores, frequent. Decays very slowly, so not uncommon in drift.