fishdentist
New Member
I am a beginner in the marine hobby, having converted from about 6 years of freshwater aquarium-keeping. I have a 30 gallon tank with a few damsels and one small piece of live rock that's been in the tank for 10 days. My question is this: on the live rock have grown a group (probably 50) of small (1/4 to 1/2") pure white tube-like creatures with small tentacles (about 8-10 per structure). They disappear when I turn off the light at night, only to reappear after the lights have been turned on for a half hour or so. What do I have on this live rock, and is it beneficial or harmful? If anyone can offer a newbie any advice it would be much appreciated!!