What is this on my LR?

[Brandon K.A]

I'm cycling my tank with LR uncured, and after about three days, I see this white stuff forming on it. what is it? it looks like mold.

 

[Brandon K.A]

No ideas? :/

 

[MINItron]

Well, it's not mold. I cans really see what you are looking at in the picture, but my first guess from your description would be a sponge. That's usually what shows up on rocks like that. The white free-form sort seems to grow well in newly establishing tanks.

 

[Brandon K.A]

I think it was a sponge too. thanks for the input.