Red cotton balls growing in refugium???

[Highside]

I have red cotton balls growing in my refugium. Does anyone have any idea what this is? Not a trace in my main tank.

 

[BMcCoy]

Matbe some kind of sponge. I have some little white ones in my HOB.


Ben

 

[c_stowers]

I agree. Probably some type of sponge. I wouldn't worry about it unless it gets real big. If it does, and dies for some reason or another, it could possibly nuke your tank.