I have those in both my tanks. I believe I read somwhere once that they are a type of sea squirt (tunicate) like Troy F indicated. They are harmless and don't seem to get out of control. My coral beauty seems to like eating them 
__________________
I retired and got a fixed income but it's broke.
Ed
_______________________________________
50 gallon FOWLR, 10 gallon sump.
130 gallon reef, 20 gallon sump, 10 gallon refugium.
10 gallon quarantine.
60 gallon winter tank for pond fish.
300 gallon pond with waterfall.
|