a little more detail would help like what color it is.. It could be a bristle worm or even brittle star if the mistakes each tentacle for individual worms.  if it is a worm indeed, then i think it could be a bristleworm.. there are many kinds of bristleworms.  only 2 types are known to be harmful(i think) to corals.. the bristle worms will eat left over food.  If it is a fire bristle worm dont take it out by hand because it can sting you and this can be irritating for a few days.  just try to take out the rock or use a trap like a pop bottle to lure the worm out.. 
		
	
		
		
		
		
			
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				Richie
			 
		
		
		
		
	
		
		
	
	
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