The Feather Duster, Sabellastarte giganteus, also known as the Fan Worm, is a marine segmented worm that attaches its calcium-carbonate tube to a rocky or sandy substrate by its base. The worm lives inside this protective tube. They then have a feathery crown that peeks out filtering the water column for food using its specialized tentacles. Their tentacles are completely retractable and can be fascinating to watch open and close. These are a common and popular addition to any reef aquarium as they require very little attention but add a certain flair to your tank. They should not be housed with aggressive fish or inverts that may nibble on their exposed tentacles.