Body long, thin and cylindrical, with at least 38 chaetigers.
Prostomium narrow, rounded anteriorly and fused to peristomium. Without ocelli. Nuchal slits semicircular, opening postero-laterally.
Chaetigers 2 and 3 with anterior collars, not incised nor with scalloped edges. From chaetiger 17 and onwards, with posterior collars with scalloped edges.
Anterior 9 chaetigers with glandular bands, anterior to parapodia and usually with an interruption dorsally. Other segments with glandular areas around the parapodia.
Notopodial capillay chaetae slightly bent, winged and finely denticulate. Some more narrow, with smooth wings. Neuropodial hooks on chaetiger 5-15 in 2 rows; in posterior chaetigers in a single row. The hooks resemble uncini (R. gracilior-detail). Last 1 or 2 posterior segments without chaetae .
Pygidium very short cylindrical, with short papillae and a broad ventral papilla.
Up to 60 mm for 30 chaetigers.
When young tube yellowish-white, when older reddish yellow, encrusted with sand, almost straight.
Light yellow-brown, transparent. Anterior glandular bands brownish-yellow to red especially on anterior segments, with white linings. Clearly white fields behind parapodia of the 4-9th chaetigers. 5th chaetiger shiny red.
From the upper sublittoral down to 1000 m deep, in mud and sand. Living in a characteristic smooth clay-tubes with a thin parchment-like inner layer. The tube is strongly incrusted with sand grains.
Arctic, North Atlantic and South Africa, Mediterranean, middle and northern North Sea, Skagerrak, Kattegat, Belts and Öresund and western Baltic Sea.