We classify a diverse range of organisms as microfossils and count anything that is generally less than 2 mm in size and best studied with a microscope. Common microfossils not covered elsewhere in t...We classify a diverse range of organisms as microfossils and count anything that is generally less than 2 mm in size and best studied with a microscope. Common microfossils not covered elsewhere in this chapter include radiolarians, diatoms, foraminifera, ostracods, and conodonts.