Christmas tree worm (Spirographis gigantea). This worm lives in a conical tube, which is attached to coral. They can grow up to 4 inches and can be seen in a wide variety of colours. The feathery structures are gills, which are covered in a sticky mucus that attracts food. Once the food is stuck on the gills it is funneled down the spirals to the worm's mouth. The gills also aid breathing for the worm.