Narrow, opaque white, subterminal pigment ring (2) encircles the translucent white tip containing cnidosacs (1). There is sometimes a translucent gap (3) between the ring and the digestive gland (4). Oral tentacles arise from the upper surface of the head (5). Internal pink jaw (6) in the translucent head.
Length 8 mm. Menai Strait, Wales. September 2011.