Christmas tree worms, Spirobranchus giganteus, are  tree-shaped tube-dwelling worms with magnificent twin spirals of plumes used for feeding and respiration. These cone-shaped worms are one of the most widely recognized sedentary . They come in many colors including orange, yellow, blue, and white and, though they are small with an average cm in span, they are easily spotted due to their shape, beauty, and color. The colorful plumes, or tentacles, are used for passive feeding on suspended food particles and plankton in the water. The plumes are also used for respiration. Though the plumes are visible, most of these worms are anchored in their burrows that they bore into live calcareous coral. Christmas tree worms are very sensitive to disturbances and will rapidly retract into their burrows at the slightest touch or passing shadow. They typically re-emerge a minute later, very slowly, to test the water before fully extending their plumes.