Featherduster question

I have a little green feather duster that's pretty much fearless. I've only ever seen him go in his tube when I siphon the sand right by him. His tube is about 4 or 5 inches long and it goes under/is attached to a piece of my rock.



I haven't seen him come out all day and when I got up close the end of his tube where his crown is is kind of ragged and broken looking. Is this normal? Is something picking on him? The only crab in there is a pompom crab...