Description

Colonies are usually thick crusts, divided into lobes. There are two colour forms, a white one and a pink one, this colour emanating from the test. The zooids are rather irregularly arranged around a series of large conspicuous cloacal openings in the upper surface of the colony. The six lobes of the oral siphon are heavily pigmented in white, as is the large atrial languet. The upper part of the branchial basket and endostyle are pigmented with white to a variable degree. 5mm thick x 20-50mm across. The most distinctive, conspicuous and easily recognised polyclinid. Most likely to be confused with Botryllus schlosseri or Botrylloides leachii, or with Sidnyum elegans. Aplidium proliferum is considered to be a distinct species by some authors. If it is a distinct entity then it looks very like Sidnyum elegans but has only 6 papillae around the oral siphon.