Natural Fossil Coral should not be mistaken for the protected and endangered coral reefs found in today's modern oceans. It is the prehistoric fossilized remains of the invertebrate reef builders that live in tropical oceans. Silica-rich waters create hardened deposits that preserve coral skeletons, resulting in fossils that are chalk-white, tan, gray, and brown as well as pink, red and yellow-orange. It has no artificial enhancements - and is an astonishing creation of nature that displays ornate and textured flower or fern-like patterns. These striking patterns are determined by the particular species of coral that became fossilized. Each stone is unique.