Brown stuff (maybe algae) on my sea sponge.

[porous_gravel]

I got a sponge a couple weeks ago. Everything seems to be going well, the sponge even attached to the rock I strapped it to. The one thing I’ve noticed, is there seems to be some algae on top of the sponge. Is this a problem? Should I move it to a lower light area?

 

[Stephen8169301]

Can you just blow it off or is it attached?