Sometimes I can be so dense......((sigh))....the rock you bought, it has a bunch of little featherdusters right? Spaced out pretty evenly too? For some reason, I thought you were talking about the duster cluster rocks where the whole rock is covered in larger dusters usually all one color. I believe what you might have instead are X-tree worms that have a symbiotic relationship with the porities coral that covers the rock.
I couldn't find my sites about featherdusters but these....
www.wetwebmedia.com/feather.htm
www.peteducation.com/catergory_summary.cfm?cls=16&cat=1900
If you have the X-mas tree worms, you will read about how hard the porities coral is to keep alive (back to this in a minute) and how without the coral the featherdusters will die (which is an accurate statement). One thing to remember with any featherduster worms is to not keep angels in the same tank with them as angels will eat the worms!
Back when I first started this hobby, I didn't have a computer so all the info that I had was what I read in books and magazines. Not much was mentioned about the porites coral and worms so when my local LFS had some for sale at a resonable price I bought the rock. Too bad that my dwarf angel (an ebili) ate most of the worms before I could stop him.....but what was really bad was that I didn't even realize that the porities is a
coral , not only that but it is a SPS coral (small polyped stony) which are supposed to be the hardest to keep and the coral needs perfect water and the correct lighting! Because I had bought the rock for the worms, I didn't even think about lighting as worms don't need any special lighting.......
Later on when I found out about the coral and it's failure in most aquariums I was puzzled. This coral has to be the toughest thing around!!! It was originally in a tank that had minimal lighting, it has gone through a bout with ich and the medication to go along with it, it's been moved from tank to tank, from higher lighting to lower, to almost non-existant, too low circulation to too high, being buried in sand by fish in the tank, being stung by neigboring corals, fish and shrimp picking at it, etc.....
The worms have long ago died out although they did reproduce at one time (young worms will fail if they don't land on the coral itself)
but I still have the coral and it is still going strong and spreading.....
So....what they do like is a moderate current and a tank that is not over skimmed or skimmed at all. They don't like being in reach of other corals that can sting them. They are filter feeders so giving them phytoplankton is good and once your tank is established, they should get plenty of nourishment from the tank itself. Lighting is not as important as you might think. Although I would not attempt to keep them in the dark, they can survive quite well with lower light levels but when more lights are added they will spread faster. They will often darken in the home aquarium and this is nothing to worry about. One thing that can be a problem is when algae tries to get "into" the coral itself. You will be able to tell this by the dark green stripes that will show up. The best way to combat this is by increasing the circulation to the coral.
If you find you DON'T have X-tree worms, then I've just rambled on an on for no reason.....but hey, I do that all the time anyway!!!