Feb 13, 2011 #1 W warvillian Aquarium Advice Activist Joined Jan 21, 2011 Messages 173 Location Tinley Park, IL I would like to know what this is? It looks like a sponge but no sure.
Feb 13, 2011 #2 mr_X Aquarium Advice Addict Joined Apr 27, 2008 Messages 17,895 Location Fairless Hills, Pa. yep. sponge.
Feb 13, 2011 #3 OP OP W warvillian Aquarium Advice Activist Joined Jan 21, 2011 Messages 173 Location Tinley Park, IL Good or Bad ?
Feb 13, 2011 #4 mr_X Aquarium Advice Addict Joined Apr 27, 2008 Messages 17,895 Location Fairless Hills, Pa. there aren't any bad sponges. they are just harmless filter feeders.