Toadstool help

[Squidly]

Could anyone tell me what could be wrong with my toadstool? It is usually the biggest thing in the tank but lately, last 5 days, it hasn't opened at all and I am clueless to what could be wrong. All my parameters are in check and its in a mid flow area with good lighting.

 

[Dav3]

Double Check alk. Also the crab on it will cause it to close up. Also looks like there is some yellowish debris on it. Blow that off.

 

[Azn_gq]

Can also be moulting/shedding. Tends to do that every now and then. See this awesome article about them.

http://saltaquarium.about.com/od/coralcare/ss/sscoralshedding.htm