Weird Patch

[Rollman]

hi everyone-
Noticed this white patch on one of my rocks a month ago. Appears to be growing ? All params are in check and all others look good.

Thanks

 

[Lovemyreef2015]

I'm not sure what I'm looking at. Could be sponge but not sure. Can you post a picture with white lights on?

 

[cloak]

A pest perhaps? (that's where it started?)