I'd try and get the BTA to move away. They will walk over anything they feel like and take no prisoners. I had mine kill a nice piece of pocilliopora last week while I was gone. It had happened so fast that my friend taking care of the tank had no idea it had happened. When I got home it was a completely clean, white skeleton. I'm sure it quickly RTN'd, and am glad it didn't get anything else. I had been given the piece as a frag and it had been growing nicely. If that BTA ever got close to my crocea, it would be no contest, the anemone has got to move!