The rock that put us on the map. While it might appear to look like others in the market, it is not. Our Reef Saver Rock is carefully sourced for color, porosity, and purity. Our cleaning process is also the best in the business. Accept no imitations and choose MR for the best quality dry rock in the business. All natural calcium carbonate rock that was once part of a ancient reef. Never any chemicals or additives. Often, you can spot fossilized ancient corals within the rock. Highly Porous and Beautifully Shaped