Prostomium of this scale-worm is bilobed with distinct or poorly developed peaks, median and lateral antennae and a pair of long palps. Two pairs of eyes, the anterior pair anterior to the line of greatest width, the posterior pair in front of the rear margin. First segment bearing one to four chaetae and a pair of dorsal and ventral tentacular cirri.
15 pairs of scales with medial crescent-shaped pigmentation; the surfaces appearing smooth, with delicate papillae along border and scattered over the surface; without microtubercles. Notopodia are small mounds with a ventral acicular ligule and numerous chaetae. Notopodial chaetae with numerous rows of spines, some short, slightly curved, with short bare tips and some longer, straight. Neuropodia are well developed with tapered, conical anterodorsal ligule and chaetae in rows (B. elegans-parapodium). Neuropodial chaetae numerous, mostly very long, filamentous with a long spinose part and capillary tips. Also beneath the acicula a few stouter chaetae present and at the bottom of the bundle a few shorter, distally capillary chaetae with capillary, feathery tips (B. elegans-chaetae).
Up to 68 mm for 38 chaetigers.
Dorsum with greyish green to brown middorssaly, with brown pigment along sides.
Circumpolar, Kara Sea to Skagerrak, deep Koster Channel.