How concerned should I be?

[wtdenk]

I assume this is some type of sponge native to the gulf of mexico? Unless it came on a frag, gulf rock is the main suspect. It's intertwining itself underneath some zoas and this gsp rock. The corals seem ok, but it seems to be spreading. I just saw a new patch underneath some rock work not near any coral.

Here is a pic of my gsp closed up at night that clearly shows the creature. When the gsp is open you can't even see it.

How concerned should I be?

 

[Lavey29]

There are mixed opinions on sponges. Some are good filter feeders. Some are invasive and choke off corals. They also can give off toxins that will hurt stony corals.

Based on that type in the pic and advanced spreading I would try to remove it.

 

[ISpeakForTheSeas]

If the corals are fine despite it growing like that, then it's almost certainly harmless (at least chemically), but you should probably keep an eye it for invasiveness/spreading too fast and for if it starts growing over and smothering the corals.

 

[bnord]

its not hurting the GSP, I would keep on watching it but not worry too much