Description: Encrusting, becoming a thick cushion (e.g. 1-1.5cm thick by 7cm diameter; thickest at the centre and tapering to the edge). "It can grow into cuplike or lamellate forms when mature" (?). Beige, occasionally yellow. Very soft and friable. Several oscules, scattered across the upper surface of the sponge, seen as dark holes in surface. Inhalent pore areas are obvious between conulose projections when seen alive.

Habitat: On vertical surfaces with moderately strong water movement. At Hake Island, Sherkin Island, on underside of boulders; "on mud, gravel, stones". Tolerant of brackish conditions in Daucleddau estuary, Milford Haven.

Distribution: "Arctic-boreal south to ca. 40°N. Mostly recorded from deep water, although type locality (Tenby) was intertidal." Known recently from Strangford Lough; Lough Hyne; Sherkin Island; Blaskets; Skomer; Milford Haven; Guernsey.

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

iNaturalist: Biemna variantia at iNaturalist World Species Observations database.