ID and good or bad

[BC Mosaic]

I got a frag of blasto on a small piece of live rock (13/4" at the widest) awhile ago. Since then this brown growth (not algae) has been starting to take over and wanting to expand. Its the fuzzy brown in the photo. Hard to take a photo because they are constantly waving in the flow. Is this what they call mermaids chalice/cup or something? You can also see that it is sending out runners which leads to the second question: good or bad?
Thanks