Please ID This growing on my Zoa's

[YellowDesmo998]

I noticed this light brown "stuff/thing" growing on a spot where zoa's once lived. It won't blow off and doesn't appear to be growing. Zoa's are directly touching it towards the right side and are open and look happy for lack of a better term. It’s been there for about a month. Any ideas?



http://reefcentral.com/gallery/data/500/24597DSC_3079-a.jpg


http://reefcentral.com/gallery/data/500/24597DSC_3075-a.jpg