I have 5 rose bubble and 2 green bubble anenomes and some times they get up and move for seemingly no reason. Last month 1 disappeared into the rocks in the back of my 180. I thought he was dead and gone. 3 days ago he showed up in the top of my live rock looking great. I had one of my first ones do it and I moved stuff and "rescued him". The next day he split 3 days later they both turned into a puddle of goo. They will move about and find a happy place just do what you have control over, make sure the water temp and quality is good. He will find the light and reappear.