What is this?

[kwan]

Some kind of red crust is spreading across my LR. It is very hard like a shell. Where they are growing, it will eventually cover the entire LR and kills off any coral that is on it. I have lost a few mushrooms and polyps already. Can anyone tell me what it is and how I can treat it?

 

[boardsurfer]

I saw a post about this a few months ago. I think we guessed it to be a type of coraline, but I'm still not sure. I have a little bit of that in my tank as well. It's pretty brittle, right? Mine is shelf-like. Someone else may help.

 

[boardsurfer]

I think a couple of people were asking for a shipment of the unwanted discards, too. Mine isn't spreading as bad as yours sounds, but it may get out of control if I don't do something about it soon. I think I'm going to take it out (luckily it's on an end piece of LR) and scrub it off with a steel-bristle toothbrush in a 10 gallon bucket of saltwater.

 

[JM]

My friend has the same thing in his 72g reef. By the looks of it we thought it was some type of shroom because thats the shape it is taking, but i have never tried to touch it to see wut the texture is like. I guess he is gonna have to scrub that peice of LR down to get rid of it before it gets too bad.

 

[Fluff]

Looks like plating coralline. I have it in my tank as well and encourage it. It's never overgrown a coral.

Moved this to the sw ID forum.

 

[kwan]

Yes, I do think it is some kind of coraline. It is brittle all right. As you can see in my photo, it has overgrown. There used to be mushrooms on that area and now they have either shrunk or died. It is covering my other LR as well and killing off anything in its path. The problem with mine is I can't take it out and scrub it because there are coral on those pieces.

 

[got bait?]

There used to be mushrooms on that area and now they have either shrunk or died

Your shrooms would have just left the area if they didn't like it there anymore. Sounds like saomething else caused the shrooms' demise.

Looks like plating coralline.

Agreed!

 

[No_Floaters]

It looks like coralline to me also. I wouldn't try to scub it off the live rock. Save your strength for scraping it off the glass!

 

[nycpassat]

Looks like plating coralline to me. Definitely somethign positive.