Description: A thick bulbous sponge, with the upper surface covered by vertical, tapering papillae. The surface is clean and smooth and varies in colour from orange to yellow.

Habitat: Most commonly found on sediment covered, upward facing rock or boulders in the lower infralittoral and circalittoral zones, associated with bryozoans and hydroids. It occurs in a wide variety of physical conditions from areas with strong tidal streams to very sheltered, silty ones.

Distribution: A common species on western and southern coasts of the British Isles.

Similar Species: May be confused with Ciocalypta penicillus and other Polymastia species, however P. boletiformis is a much thicker cushion that stands proud on the rock surface whilst other species are low-lying encrustations.

Key Identification Features:

• Presence of tapering papillae.
• Orange/yellow colour.

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

iNaturalist: Polymastia boletiformis at iNaturalist World Species Observations database.

WoRMS: Polymastia boletiformis at World Register of Marine Species. Accepted name: Polymastia boletiformis (Lamarck, 1815). AphiaID: 134194.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Polymastiida; Polymastiidae; Polymastia