I just noticed something in my live rock today. I saw something that looked literally like puff of smoke coming from the top of my lr
and then it would dissipate in the water. It did it a couple of times and when I looked closer I saw this little green thing with long green antennas. It looked like it was compressing itself and each time it did it, a puff of smoke came out. I couldn't really get a good look at it, it was kind of hidden in a hole. After it did this it went back in. I was unable to take a picture of it at the time and I have no idea where it went now. Any ideas what it is, and is it bad for my tank?