I had the same thing occur with a frogspawn. I had a branching one with 2 heads. I lost both heads due to bad water quality, but left the skeleton in the tank. A few months later I noticed a green glowing dot that was only visible just before lights out. Eventually that dot grew into a head and today it is a softball sized colony with another colony that grew from a baby that it dropped off. It is a great feeling when you manage to turn it around before the coral completely dies.
