Green bubble tip anemone help =(

[fscmocsaj]

So I got an anemone (Green bubble tip) last week and he hid underneath a rock in the cave my coral beauty sleeps in. His mouth is closed however his tentacles stayed short.

This morning I noticed he shriveled up and went farther into the cave and he is about half the size. It also looks like there is white stuff coming out from the center of the anemone.

Is it dying? It is still attached to the rock.

 

[fscmocsaj]

Tank is close to six months. No ammonia, nitrites, 10ppm nitrate. My SPS corals are doing well so I know my water quality is good.