There are more than one type, and when it goes sexual it basically melts. So everything it has used to grow gets dumped back into your tank. Lighting 24/7 will usually prevent this, but it's a good idea to switch out for chaeto so you don't have to worry about it in the future.
I second the chaeto. Its all I've ever used, and it's so easy to maintain. every few months, I tear out half and give it to my LFS. it grows that fast.
__________________
Former advisor and planted tank geek...life's moved on though.