What venomous marine worm has bristles that give it the name fireworm?

The venomous marine worm whose bristles give it the name fireworm is the bearded fireworm.

The bearded fireworm is Hermodice carunculata, a marine bristleworm in the annelid family Amphinomidae. Its body is flattened and segmented, with paired parapodia, gills and conspicuous clusters of pale bristles along the sides. When disturbed, those bristles flare outward and can penetrate skin.

The bristles deliver a neurotoxic irritation that produces the characteristic burning sensation behind the common name. Contact may cause intense pain, tingling, redness, nausea or dizziness. The worm is usually slow-moving and poses little threat unless handled or brushed against accidentally.

Bearded fireworms live in shallow tropical Atlantic and Mediterranean waters, on reefs, rocks, sand, mud, seagrass and drifting wood. They average about 15 centimetres but may reach 30 centimetres. “Fireworm” is a broad common name, so it can refer to related amphinomid worms; the quiz’s specific canonical answer is the bearded fireworm, not a ragworm, lugworm or bobbit worm.