Colonies are often very dense and typically between 25-80 mm in length. They appear transparent, white, cream or yellowish in colour. In the creeping form, colonies closely adhere to the substrate, whereas erect colonies are raised off the substrate. The zooids form feathery or bushy clusters along a thick cylindrical stolon (up to 0.3 mm). The species is commonly found in the lower intertidal and shallow subtidal on algal or hard substrata throughout the NE Atlantic, Mediterranean and east coast USA.