Advice? Any clue what this is in my frogspawn?

This is the second time I've seen this occur in the several years I've had a frogspawn. Seemingly out of nowhere there is a large white balloon-like growth:

Anyone know what this is and what causes it? I'm not overly concerned since it came and went without issue previously.. but I am curious.

Thanks!

 

Very interesting. It must only do that on occasional splits. This was just one surviving head that broke off from my softball sized colony when I sold it before my move. It definitely doesn't do that for each new head.