Dinocysts or dinoflagellate cysts are typically 15 to 100 μm in diameter and produced by dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils.[1] Organic-walled dinocysts are often resistant and made out of dinosporin. There are also calcareous dinoflagellate cysts and siliceous dinoflagellate cysts.