fungus on rock

[chapel210]

My rock looks like it's growing some type of mold or fungus . Looks kind of like a white and black substance? Unable to post a pic at the moment. Anyone have any ideas of what it is or how to get rid of it?
Thanks

[CoryDude]

Sounds like a type of sponge. Is it on the underside of the rock? Should be harmless in my experience.

[jpond83]

i have had the the same thing since i set up my tank i believe it is a sponge

[chapel210]

The way the rock is aet up its facing up, but this is spreading across the rock and onto the sand.

[CoryDude]

Are you still having problems posting a pic?

If it's spreading that fast on the rock/sand bed, then I'd get rid of it. Start syphoning out as much as possible. You might even want to pull affected rocks and lightly scrub/rinse them in separate buckets.