Seven large tripinnate gills in circle around white anal papilla fringed by four brown elongate tubercles (1).
Translucent gills tinted as mantle. On this brown specimen, the usual opaque white along each side of midrib forming a star is tinted brownish (2) and the often pigmentless lamellae are opaque white (3). Length of animal 11mm, Menai Strait, Wales, March 2015.