Fairly stiffly branched fronds growing from a crust-like discoid holdfast, covered with small branchlets arranged in whorls. Maximum length usually about 15 cm. 

Original publication: Agardh, C.A. (1817). Synopsis algarum Scandinaviae, adjecta dispositione universali algarum. pp. [i]-xl, [1]-135. Lundae [Lund]: ex officina Berlingiana.

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Draisma, S.G.A., Prud'homme van Reine, W.F. & Kawai, H. (2010). A revised classification of the Sphacelariales (Phaeophyceae) inferred from a psbC and rbcL based phylogeny. European Journal of Phycology 45(3): 308-326.

Mazariegos-Villareal, A., Riosmena-Rodrigues, R., Rivera-Camacho, A.R. & Serviere-Zaragoza, E. (2010). First report of Cladostephus spongiosus (Sphacelariales: Phaeophyta) from the Pacific coast of Mexico. Botanica Marina 53(2): 153-157.

Sánchez, I. & Fernández, C. (2005). Impact of the invasive seaweed Sargassum muticum (Phaeophyta) on an intertidal macroalgal assemblage. Journal of Phycology 41: 923-930.

Womersley, H.B.S. (1987). The marine benthic flora of southern Australia. Part II. pp. 481, 169 figs, 1 table, 8 plates, 4 maps. Adelaide: South Australian Government Printing Division.

This is the type species (lectotype) of the genus Cladostephus. 

Basionym:Conferva spongiosa Hudson

Type locality: England (Silva, Basson & Moe 1996: 574).

Lectotype: BM (Womersley 1987: 185).