Reproducing or illness?

[Docpayne82]

Came home today and noticed one of my zoas had dropped off from its colony to the sand bed in another part of the tank. The colony looks great and the one on the sand bed is nice and open too. Is this a method of reproduction by dropping babies around the tank or some kind of illness?

 

[mkutsch]

My guess is that either flow or a hermit or such accidentally ripped it off. I very highly doubt that this is the result of splitting or reproduction, but who knows.