The Feather Duster (Sabella sp.) 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.