Description: Low cushion with tall sides and rugose upper surface. Larger specimens may become massive-globose, to ca. 15cm across, and are often angular with ridges and crests. (Cushion forms are also described in the literature, and Arndt (1933) refers to a crust-like form). Greyish-white, through orangeish, to almost rose-red. The colour can vary within a single specimen, because of the variable combination of a translucent whitish ectosome and light brown choanosome. Firm; slightly compressible, elastic. In situ, oscules are usually borne on long, white, translucent, almost vermiform chimneys. These are not always present, but there may be two or three per sponge. They are fragile and collapse on collection, leaving whitish patches.

Habitat: On wave exposed circalittoral rock (often where horizontal when in the "open"), to at least ca. 60m.

Distribution: A south-western species in the British Isles. Known recently from Salcombe (Prawle Point), Lundy, Skomer, Sherkin Is., Calf of Man, Rathlin Is. (The record of Rhaphidostyla incisa reported by R.W.B. van Soest from Sherkin Is. (Irish Nat. J. 20, (1), p. 1-15), was found on re-examination to be Tethyspira spinosa (R.W.B van Soest, pers. comm.)). Reported from Fowey Harbour by Bowerbank. "Continental Channel coast", ?Brittany. Records from other sites in the British Isles would be of very great interest. Do not over collect.

Distribution Map from NBN: Tethyspira spinosa at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Tethyspira spinosa at iNaturalist World Species Observations database.