I once had some wood that had the same fur but way worse. I got rid of it b/c even if it was cleaned it came right back. It was years ago but for some reason I think I found out it was pine. What tipe of wood is that?
If possible, take it out and boil the drift wood for a couple hours. If you meant 9 foot than I can't help you there! That should take care of the algae though.
I have a piece of driftwood that used to do that a long time ago. Never seemed to harm anything and it went away after it was left out of the tank for a few weeks