View Full Version : Purple hard stuff on coral???

03/14/2017, 10:48 AM
I don't know what this coral is but it once covered the entire area. I think it's a soft coral?

Now there is what looks like purple growth on it. I've touched it and it's hard and coarse. Any ideas?


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03/14/2017, 10:54 AM
Here's with whites only on.

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03/14/2017, 11:39 AM
Could be a barnacle of some type.

03/14/2017, 01:17 PM
What you have there are green star polyps. (Briareum sp.) Why there's a bare spot right in the middle of them I don't know, but it looks like some sort of sponge has started to take over. That purple stuff your seeing is probably just Coralline algae.

03/14/2017, 01:30 PM
Thanks AI Simmons. So, the circle area is actually the top of a round frag plug. The coral was only there at first when I bought it from LFS, then eventually spread to the rock after I glued it. However, in the last month or so this purple patch has started and then grown. But to be honest I dont know if the patch is growing or the coral receding. :/ I am hoping its not coral decay or some "bad thing".

03/14/2017, 01:36 PM
Did star polyps previously occupy that spot? GSP have a nice purple mat they lay down and sprout out of. You've probably seen it when they retract. In a previous tank of mine I saw them extend the mat before the polyps became visible. I also saw them recede from an area they did not like and after the polyps vanish the purple mat decays. As it decays it exposes the darker purple inner mat.

I think that is what may be going on here. Something in that location is upsetting the GSP and it is receding. Could be light or getting blasted by a current from the power head.

How long have you had it in that location?

03/14/2017, 01:47 PM
Yeah that whole circle is a frag plug and had GSP on it.

So they are decaying there? Interesting...

Well they are growing like crazy across this rock. Up and down. Left and right. This little patch is the only horizontal surface to the light. Flow is fairly indirect but I thought it flow didnt matter much to GSP. :/ I just hope it wasn't something bad that was eating it away but it sounds like it is not.

03/14/2017, 01:58 PM
You might want to get yourself a razor blade and see if you can remove anything from that bare area. If it wants to peel off then it's probably the mat from which the GSP grow from. If not, then it might be some type of sponge. These have been known to smother various corals on occasion.

Diana A
03/14/2017, 02:47 PM
It looks like coralline algae on the plug.

03/15/2017, 01:44 AM
+1 for GSP matt...the polyps have receeded for some reason, possibly died off, and coralline has grown over the top. Any livestock that could be nipping at it?

03/15/2017, 06:01 AM
Thanks everyone again for chiming in. Occasionally I see blue/red hermits sitting on the flat part doing their thing. Other then that no.