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. 

Original publication: Stackhouse, J. (1797). Nereis britannica; continens species omnes fucorum in insulis britannicis crescentium: descriptione latine et anglico, necnon iconibus ad vivum depictis... Fasc. 2. pp. ix-xxiv, 31-70, pls IX-XIII. Bathoniae [Bath] & Londini [London]: S. Hazard; J. White.

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Cremades, J. (1989). Ethelia fissurata (Crouan frat.) Denizot y Chaetomorpha pachynema (Mont.) Mont. in Kütz. en las Islas Baleares. An. Jard. bot. Madr. 46-1: 341-344.

Dixon, P.S. & Irvine, L.M. (1977). Seaweeds of the British Isles. Volume 1. Rhodophyta. Part 1. Introduction, Nemaliales, Gigartinales. pp. xi + 252, 90 figs. London: British Museum (Natural History).

Loiseaux-de Goër, S. & Noailles, M.-C. (2008). Algues de Roscoff. pp. [1]-215, col. figs. Roscoff: Editions de la Station Biologique de Roscoff.

Maggs, C.A. & Guiry, M.D. (1982). The life history of Haematocelis fissurata Crouan frat. (Rhodophyta: Sphaerococcaceae). British Phycological Journal 17: 235.

Serio, D., Alongi, G., Catra, M., Cormaci, M. & Furnari, G. (2006). Changes in the benthic algal flora of Linosa Island (Straits of Sicily, Mediterranean Sea). Botanica Marina 49: 135-144.

Type species: This is the type species (lectotype) of the genus Sphaerococcus.

Type locality: Cornwall, England Holotype: BM-SL