Cephalothrix rufifrons (Johnston, 1837)

Length up to 9 cm, width up to 0.2 mm. Body pale orange, somewhat translucent, thread-like, circular in cross section. Head not differentiated, usually eyeless (newly hatched juveniles do, however, have two black eyes), its outermost apex with a small, brightly orange-coloured spot. Mouth situated far behind brain, visible as a knob as wide as the body.