Help ID PLEASE

[jokerjohnson]

Sorry for the crappy photos, hard to get a good one. Tank is 1 1/2 years old. Mixed reef 40 gallon cube. 10 gallon water change EVERY week.
I just noticed this weird like gray almost mold like fuzz growing in small splotches on my rocks.
Not sure what it is, would appreciate advise please

 

[WheatToast]

Sponges. Generally harmless filter-feeders. Their openings are called oscula.

 

[KrisReef]

Looks to be a sponge, just like @WheatToast said