Strange stuff growing around my green star polyps....

[jtdesigner]

My green star polyps were doing great, but this weird stuff has grown around it. My lfs wasn't sure what it was. I don't think the gsp is growing, as it's supposed to send out a "purple blanket", not sure if I should pick this stuff off or what. Anyone have any ideas? thanks in advance!

 

[Tuan’s Reef]

take another pic with whites only. Is the stuff white? Have you tried peeling it off ? maybe invasive type sponge

 

[Quietman]

Poriferan sponge? Take a look at this thread.