Not the usual shape of a worm ? The feather duster worms have a series of feathery tentacles on top that are used to filter nutrients from the water. When threatened by predators, they quickly withdraw deep into their tube homes.
Another specie, the Christmas tree worm, has a very ornate arrangement of feeding tentacles – they eat microplancton – that can be found in a wide variety of bright colors. When disturbed (changes in ligh, water presion, if you attempt to touch it, for example) they are quickly withdrawn into the tube. Young worms settle on coral heads, meanwhile the worm occupant secretes additional tube material to keep pace with the coral. New coral growth quickly surrounds the tube.
Spaghetti wormsInhabit reefs and adjacent areas of sand and rubble. Leave in tubes constructed of fine sand and mucus. Tentacles are retracted when disturbed.
Firewrom, when disturbed display bristles, which can easily penetrate and break off in skin, causing a painful burning sensation and irritated wound.