i'm betting your rock is live. if you are referring to the visible fauna that lives on the outside of the rock, dying because of lack of light, then don't worry about it. the bacteria on the surface, and in all the nooks and crannies of the rock are what makes it "live".
alot of times, you are better off without all that plant life, and the sponges will probably die off when you get the new light anyway. the good news is, new stuff will grow later on down the line.