Here is a very colordul Cryptozoon Stromatolite specimen from the Ordovician of Colorado. Authorities believe that this stromatolite was formed by masses of green or red algae (Chlorophycophyta). This particular stromatolite has been dated to over 400 million years old! This slab has been highly polished on both sides for optimal display. The colorful, structured mineral replacement is clearly defined and makes for a unique presentation. This is a beautiful example of this extremely unusual stromatolite from Colorado.