Hawaiian Feather Duster out of tube

I just bought my first big feather duster yesterday from The Aquarium.  I brought it home, took about 45 minutes to acclaimate it, made sure it never came in contact with air (I was not sure if it would harm it not).  It showed its head in the bag!  I put it in the sand in a low flow area that is protected by LR on three sides, buried about 1/2 of it in the sand and left the top 1/2 sticking straight up.  It showed its head in a matter of seconds.  It looked great all night.  This morning it looked like it wanted to come out of its tube since I could see about 1/4 inch of the worm itself.  I went up to the hospital to visit my daughter-in-law.  When I came home again, the worm and feather head was completely out of the tube and has buried all but about 1/2 inch of the worm (However long it is!) in the sand pretty close to where I had placed it. 

If nothing else (Including hermit crabs) attacks the worm, will it be all right?  Has anyone else had experience with this before?

Will the hermits attack the worm? 

I do not have any fish that will try to eat it or bother it, so I am not worried about them.  However, those crabs are something else!

I question whether the FD worm actually came all the way out of its tube. From what you said (& didn't say), I suspect it may have cut the tube underground and is forming a new upper tube. This is even more likely if the original tube is 5 inches or longer.

Which one of these does it most closely resemble?





The FD in the top pic used to have a tube that reached about four inches above ground, but in a day or two it cut off the top three inches.