Milky white substance

[szulluke.ls]

Hi Guys
My friend asked me to post this. He had a milky white substance leaching out of his live rock.
Any idea what it might be? I will post a pic when he sends it over.
Thank you

 

[NowGlazeIT]

Could be so many things. What comes to mind for me would be spawning from hitchhikers. Example if he has a bunch of brittlestars

 

[reefndude]

Snails will also do the same