Description: This is a massive sponge forming rounded lumps up to 30cm in diameter. It is often inconspicuous due to being covered with silt and overgrown by other sponges, tunicates, etc. The surface is rough to the touch and if cut a well-developed, spicule packed rind 3mm in thickness is clearly differentiated fronm the softer creamy interior.

Habitat: In dark places, beneath overhangs or in caves. Found both in tidal streams on the open coast and in very silty sheltered conditions in sea loughs.

Distribution: Widespread in the NE Atlantic from Shetland south to the Mediterranean.

Similar Species: Easily confused with Stryphnus ponderosus which has a thinner surface rind and is usually more encrusting.

Key Identification Features:

• Massive rounded sponge with sandpaper texture to surface

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

iNaturalist: Stelletta grubii at iNaturalist World Species Observations database.

WoRMS: Stelletta grubii at World Register of Marine Species. Accepted name: Stelletta grubii Schmidt, 1862. AphiaID: 133974.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Tetractinellida; Astrophorina; Ancorinidae; Stelletta