Live rock fungus or not

[sherroddr]

On one of my live rocks there is somthing growing on the bottom of it. There is about a 2" between the bottom of the rock and the sand bed. One of my goby's hangs out in there. It looks live mold and is a light frosty green with some yellow spots where the rock was picked up and it started spread to the next rock. It grows flat on the rock and speads like a mat. It is kinda spongy but not much. I have never had a sponge in my tank so I don't really know. Thanks sherroddr.

[scubasteve247]

a pic maybe? always helps....