eIn my octo tank I have only a couple of things to break the live rock look. A few green metallic mushrooms (3) and a sea matte. I was unware that octos like to eat sea mattes. After see him drag the sea matte (its mounted on a rock) down to the sand bed he jumped on top of the coral like he does all new "posessions" and parachuted it. He had never fooled with this coral previously, or dislodged it. I couldnt get anywhere near it without him changing colors to match the sand. etc. He did this for about 3-4 hrs. When I finally tried to take it away by hand we had a tug-of -war and he desprately tried to drag it into his den. I see why, he was using it for food. He ate half the matte!!! I have included a pic from before the incident. I have also included an "after pic". The coral has closed up, which would be normal for it during times of the day, but when he came off of it after 3-4 hrs, it was half gone and the perimeter of the missing part had long serated marks from the top to the bottom like it had been knawed or eaten, like teeth marks on a chocolate bar. The second pic shows this although not in great detail as my zoom on my camera stinks. Can anyone shed any light on this or other corals that might not be appropriate for an octo tank.