Although they come in many sizes, featherdusters are a popular addition. Larger ones called Hawaiian Featherdusters are very common. A worm resides within a tube, and extends a crown of "feathers." These are used for filter feeding. Although they don't need light to live, feather dusters quickly retract within the tube, pulling the crown in with them, when they sense danger due to a sudden change in lighting or current. Feeding phytoplankton every other day suffices. Reef-safe.