A colonial ascidian consisting of groups of very flat-topped lobes closely pressed together, with sand coated sides. The upper surface is clean, and brown in colour. 5mm thick x 10mm diameter. The name used here for this species is somewhat doubtful, but it is a distinctive entity.

Arctic Ocean, Atlantic, Belgian Exclusive Economic Zone, Canada, Canadian part of the Arctic Ocean, Cobscook Bay, European waters (ERMS scope), Grevelingen, Gulf of Maine, Irish Exclusive economic Zone, Minas Basin, North West Atlantic, Oosterschelde, Scotland, St. Lawrence Estuary, United Kingdom Exclusive Economic Zone

deep water off Rhode Island and Cape Cod; lower intertidal zone in Bay of Fundy and northward

Bay of Fundy to Cape Hatteras

An Arctic-Boreal species

Reported to be a northern form in the British Isles, rarely recorded.

Known from rocky shores.

infralittoral and circalittoral of the Gulf and estuary

Depth range based on 63 specimens in 1 taxon.
Water temperature and chemistry ranges based on 22 samples.

Environmental ranges
  Depth range (m): 0 - 3338
  Temperature range (°C): 1.484 - 23.720
  Nitrate (umol/L): 0.501 - 38.842
  Salinity (PPS): 32.468 - 36.080
  Oxygen (ml/l): 2.381 - 7.728
  Phosphate (umol/l): 0.100 - 2.922
  Silicate (umol/l): 0.805 - 89.455

Graphical representation

Depth range (m): 0 - 3338

Temperature range (°C): 1.484 - 23.720

Nitrate (umol/L): 0.501 - 38.842

Salinity (PPS): 32.468 - 36.080

Oxygen (ml/l): 2.381 - 7.728

Phosphate (umol/l): 0.100 - 2.922

Silicate (umol/l): 0.805 - 89.455
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Apparently a species usually found in the circalittoral, often in sand-scoured sites.

Originally, the ascidian Aplidium glabrum only occurred in cold to Arctic regions. It is a colony forming ascidian with a spongy appearance. The colonies are shaped as crusty lumps, are somewhat transparent and can be grey, yellow or even orange. On the Belgian coast, since 2000, the species is found in the marina of Zeebrugge, where it grows on ropes, quays, pontoons and other hard substrates.