I agree...I tend to not like sponges...they are one of the liverock hitchhikers that sway me toward perferring dry rock. Once some of them start growing they can become a real pain. I had a black one that was impossible to kill...even after removing a rock and drying it out, it still came back to life. I currently have a yellow one spreading in the shadows along the back part of my tank. Fortunately it hasn't spread to the areas with corals yet.