The upper part resembles an inverted "J", with the outer surface being reinforced with shell fragments and tiny pebbles which are cemented in the style of an overlapping mosaic.

Each segment bears a pair of yellowish-brown, oar-like parapodia with green speckles, which contrast with the bright red gills[5] or "plumes" which endow the worm with its more common name, resembling a Christmas tree in rare cases.

Its range extends from Cape Cod southwards to the West Indies, the Caribbean Sea, the Gulf of Mexico, Trinidad and Tobago, Venezuela and Brazil.

[2] Diopatra cuprea is an omnivore and scavenger; it feeds on algae as well as on small invertebrates such as copepods, gastropod molluscs, barnacle larvae and hooded shrimps, some of which tend to grow on the exterior of the tube.

[7] The worm actively creates a flow of water through the tube to increase oxygenation, and haemoglobins in the interstitial fluid are used as respiratory pigments.