Coral Precious coral or red coral is the common name given to Corallium rubrum and several related species of marine coral. The distinguishing characteristic of precious corals is their durable and intensely colored red or pink skeleton, which is used for making jewelry. Red corals grow on rocky sea bottoms with low sedimentation, typically in dark environments—either in the depths or in dark caverns or crevices.
Sandstone is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black.