Brown algae on rockwork.

Does anybody have any idea what kind of algae this is growing above my Red Planet and what I could do to get rid of it. It will grow on my back glass and rockwork real similar to coralline algae it grows in thin layers with a peac like fuzz to it. Its extremely difficult to scrape off the rockwork and dont seem to die for nothing.

 

bump

 

Is it hard to the touch.....almost like coralline? I've heard of a sponge that grows in a similar fashion as to what you have, but the one I saw in another thread was red in color, and yours is just like you say, brown.

 

Its not really hard to the touch, but if is scrape it off my back glass it actually breaks away like coralline.