New tank live rock going grey

[bigfish]

I started a new tank about a month ago. Every is doing pretty well water is tested and looks good. Started with 10yr old live rock some zenia, mushrooms and sponge , which is the affected section. Which is fairly small (1x2 inch) can any one tell me what they think this is. The section also has a colony of small white worms that curlled up and dont really move.