A strew slide of fossil marine diatoms from Kamischev, Russia. Prepared by Watson and Sons. Wide range of interesting species. A higher magnification image is shown of what I have told is probably a siliceous dinoflagellate cyst. More can be read about them here – Siliceous dinoflagellate thecal fossils from the Eocene of Barbados, Harding, I.C. and Lewis, J. 1994. Siliceous dinoflagellate thecal fossils from the Eocene of Barbados. Palaeontology. 37, pp. 825-840. A pdf of the article can be obtained here. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo NA 1.40 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 18 images stacked in Zerene (Pmax).