Last night my feather duster was doing fine. This morning it is gone... tube and worm. Not a clue. Have a small anemone crab, one hermit crab, two fire shrimp and one cleaner shrimp. None of the fish have a reputation for dining on feather dusters. It is a 20-gallon long tank that has a history of being quite stable in water parameters (though I will do a full scan today). a week ago, another small feather duster worm departed its shell and another feather duster stayed in it shell for a few days. Any thoughts.