help nuisance algae

[xpawn]

There's some type of algae growing on one of the rocks in my tank. it's not growing everywhere just appears on one rock. The color of the algae is black and feels like velvet when touched. I dont have a camera that's good enought to get a good picture of it yet. I just noticed it last nite, I'll do some water test tonite. Anyone have any ideas on what type of algae and how to get rid of it?

 

[Travis L. Stevens]

Not without a picture. If it's black, I suspect that it is actually a sponge.