Real Reef Rock is our standard reef building rock. It is very light, porous and full of holes and crevices. It is three dimensional in shape and comes in many natural shades of purple, pink and red. It replicates the look, feel and function of coralline encrusted coral skeleton rock. It's made from all natural reef eco friendly materials and grown in greenhouses to become a bio-active rock, without the nuisance pests and hitch hikers commonly found on wild rock. This rock is great for Marine Reef and Fish only aquariums. Not suggested for Freshwater, as it holds a high stable pH. Rock is then dried and packaged for shipping.