Found in a core of ancient Black Sea sediments, the dead organic cell inside this coccosphere has reacted with chemicals in the seawater to form crystals of the mineral pyrite. The presence of marine coccospheres in Black Sea sediment layers has been used by scientists to date the first colonization of the area by the ancient Greeks. (The sudden massive incursion of the Mediterranean Sea that created the Black Sea about 8300 years ago has been proposed as the foundation of the legends of Gilgamesh and Noah's Flood.) SEM x 27,000.