STROMATOLITE, Fossil Algae, Utah F1745 - STROMATOLITE, Fossil Algae, Utah. Stromatolites are the oldest known fossils on earth. These specimens are over 500 million years old. Stromatolites are fossilized Algae. Division: Cyanophyta. Cyanophytes are commonly called blue-green algae. They are not members of the plant kingdom, but are included with bacteria in the kingdom Protista. From Utah. GREAT PRICE $6.50  (You can always remove items from your cart later if you wish)