I have 2 a NEST grouing in my tank is someone know what is it, and what's grouing inside , i have it about 3 weeks but now its realy looks like soon somethink or some one is on the way out
Yes, that is a sponge, a filter feeder. Very common on the underside (or dark side) of your live rock. Good to have some in the tank. Nothing to worry about
3 months is good They are a positive sign in a reef tank! It sounds like your tank is doing well. They are nothing to be concerned with - if you didn't have them starting to grow I would be concerned
I have a bunch of these guys in my tank as well. That's great that the're a good sign although I must admit they are somewhat unsightly. Is there anything that eats them?
There are several critters, and some fish, that eat sponge but we tend not to keep them in our tanks. After thei food supply runs out, it is very hard to keep them alive. Its best to just leave it be. As Kathy stated, the are filter feeders and will help keep your water clean.