My tree coral usually shrivels up and becomes dark purple at night. Then during the day it really opens up and is a nice fleshly pink color. The last two days is is just limp somewhat shriveld and dark purple. This was the first piece of coral I Put in my tank and it grew to about 3 times the size hat it was when I bought it. he only thin that has changed is I recently added frog spawn (put on the other side of the tank so it is not in reach of the tree coral) and I added 1 purple gorganian (sp?). I took a picture of what it looked like this morning - but I won't have time to download it until tonight. When I get home I will take another one.