Here's a description of what happened. It produced what is called a satellite daughter colony and it may continue to do it. They are products of asexual budding where a tentacle of the parent becomes incused with a calcareous nodule that grows until it is sufficiently weighted to break away from the parent. At that time, it will take up residence on the sand bottom as a free living, individual colony. This mode of propagation seems to be common in the wild and is presently the most successful way to raise it in captivity too.