Help I.D please

[jsg3050]

Hello I have spotted this on one of my DR pieces, it seems to be live, I tried to put my finger near it and it darted back into the hole

 

[Autumnsky]

You meant dry rock? You brought it home actually dry?

Did you put any live stuff in there?

 

[Andy Sager]

It appears to be a feather duster type worm. A filter feeder with nothing to be concerned about. These types of worms create holes or tubes for themselves to hide in and when in tidal areas, where the water reseeds to the point that the rock is totally exposed to air, worms and the other animals that live within these rocks need a way to live until the tides change 6 hours later.