Funny you should mention that…I bought that sponge! I've had it in my tank for a month or two. Right now it's sitting on the bottom on the sand. It's attached to a frag block. It looks nothing like the picture, at this point, but hopefully it will color up. Once I rip the caulerpa off the back wall I plan to split it up and place it on the wall. If it colors up like the picture I'll be a happy camper.