We have ours wedged in between rocks, they don't move. I'm not sure about yours but ours has mouths on it, 4 or 5 of them. But ours is an Octobubble, Bryan at Logical reef told us he fed it a whole krill every other night.
From the looks of our octobubble there is no way it can move, it's not an anemone, I can see how it could be confused though. Reefrunner had told me to keep it off the sand it can get sand in it and get infections, we have ours on rocks.
You have a beautiful one there!
From what I read they are found in shady areas, but have no problems with light.
A great book to help you out would be this one Aquarium Corals Selection, Husbandry and Natural History by Eric H. Borneman
Reefrunner had suggested that to me. So I purchased it though AA by using their link on the front page of AA at the bottom to go to Amazon.com I wanted to give them something back for all the help. I'm so glad I did, it helped me know what their location, capitive care, how hardy they are what they eat and so on.
Hope it opened back up for you.