Description: This solitary ascidian is found partially buried in clean gravel or shell gravel, protruding slightly from the surface. The siphons are long and tapering in expansion. The test is covered with fibrils which trap and adhere to sand particles.

Habitat: Most records are from moderately exposed sites with tidal streams.

Distribution: Found all round the British Isles and may be frequent in suitable localities but rather local.

Similar Species: Molgula occulta lives in more muddy sediments and Molgula oculata in coarser sediments. Both have shorter siphons and are less conspicuous than this species.

Key Identification Features:

• Buried in sediment singly or in mats
• Test covered with fibrils attaching particles of sediment
• Siphons long and tapering

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

iNaturalist: Polycarpa fibrosa at iNaturalist World Species Observations database.

WoRMS: Polycarpa fibrosa at World Register of Marine Species. Accepted name: Polycarpa fibrosa (Stimpson, 1852). AphiaID: 103902.

Classification: Biota; Animalia; Chordata; Tunicata; Ascidiacea; Stolidobranchia; Styelidae; Polycarpa