I am helping a friend set up a Reef Tank, and I was wondering if their is something that looks natural (no lighting diffusers) that makes a nice flat, or flattish shelf to attach corals to. I was thinking either a flat natural rock like slate (although probably some kind of limestone or volcanic rock. Would like a list of flat rocks that work in reefs?) Maybe a light diffuser rapped in a reef safe polymer or clay. Or they have Cordierite shelves for kilns, apparently cordierite is used for some aquarium décor. Any other suggestions?
