Coccosphaerales

unicellular algae responsible for the formation of chalk Coccosphaerales (Coccosphaerales) is an order comprising closely related families of organisms. It contains 2 families with 5 known species. This includes the family groups Calyptrosphaeraceae, and Deflandriaceae. It belongs to Prymnesiophyceae (Prymnesiophyceae).