I have seen many set ups in the uk of native marine life using limestone rocks such as the kind that are all over the beaches. I have also visited a local aquarium where amongst the displays was a warmer water set up that had large local grey limestone as the base rock with sensitive fish and inverts.. What is it that stops this being used in display tanks? I can not see one on the image search. It is much better for aquascaping purposes. Is it a fashion thing, or because of the filtration pluses with regular live rock?