Please help - bare green patches on GSP

[russmenard]

Hi everyone. I have two green patches on the purple mat of my GSP. There are no GS Polyps on the patches but I have seen a couple of small, clear tube-like protrusions. Is this a pest? Some of the polyps adjacent to the bare patches don't seem to want to open but the coral overall seems to be doing very well and is spreading. I have attached a couple of pictures. Sorry, they're not great but in one you can see the clear tubes if you look closely. Any ideas? Do I have a problem that needs fixing or do I just ride it out?

 

[JaaxReef]

Looks like a type of sponge irritating it. You could try to remove them? Beneficial to the tank, but can certainly irritate some corals.