Whats on my flower pot coral?

[wfo115]

I have had this coral for about 2 1/2 months in the same spot in my tank which was kind of high flow. All has been good up in till my clown fish started to think it was anemone, then it started to not extend its polyps as much. This has been going on for about a month. So four days ago I thought I would move it to a lower flow area of my tank, now I started to notice this spider nest looking covering on it any idea what it is and what I should do, I already moved it back to where it was originally anything else I should do? Below is a picture from about 1 month ago and another picture from today with the coating on it.

 

[devil dog]

When do you do water changes and how much do you do? i would say that it is not getting something it needs...

 

[jackri]

I would've left the clown alone with it -- still extended and cool to watch clowns attach to something (long as it wasn't going to kill it and it still looked ok).

 

[stanlalee]

flowerpots dont do well when clowns host them (well they dont do well period but worse when clowns irritate them and keep them closed).