I have a small zoa frag, about 4 heads. It was a survivor of when I had an outbreak of some pest that ate the main colony. Somehow this little guy, with only one tiny head popped up next to a rock in a shaded area. That was about 2 months ago. Now it has 4 heads and last week it appeared to me it had moved away from the rock a little. Yesterday it was quite a ways away, and today it appears to be heading towards a rock with more light. Are my fish moving it? Do they move on their own?