Here is one of the ones I was able to find. There was another one which was alot more detailed but I don't feel like wasting my time.
So as you can see it can go either way. They split for different reasons including from stress, or from being content "propitious circumstances".
"Clones and asexual fragmentation of different degrees can result in the replication of many individuals from one. This can be a natural event, w/ no input from the hobbyist themselves... derived from either too much stress, or propitious circumstances."
BTAnemRMF