A flattened segmented worm to about 15 cm (6 in), green to reddish brown, with a tuft of brilliant white bristles on every segment along both sides and red gills between them. The bristles look soft and are anything but: they are hollow glass-like chaetae that break off in skin at a touch and release a toxin, producing a burning that lasts hours and an itch that lasts days.
Removing them takes tape rather than fingers, and rubbing drives them deeper. The worm feeds on coral, anemones and anything dead it finds, working over the reef openly after dark - one of the few animals here that can eat fire coral and stinging hydroids without difficulty. It is slow, entirely uninterested in divers, and dangerous only through contact, which makes it a good argument for keeping hands off the reef at night. Torn pieces regenerate, so a worm cut in half becomes a problem twice.
- flattened segmented body with white bristle tufts down both sides
- green to reddish brown, gills red between the bristle tufts
- moves slowly and openly over coral after dark
- length up to 15 cm
