An arrangement of fossil diatoms from California, USA. Prepared by Northern Biological Supplies (NBS). 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 35 images stacked in Zerene (Pmax). I also selected one (top row, second from left) which I think is Stellarima steinyi, and imaged that at higher resolution using a 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 78 images stacked in Zerene (Pmax). This is a tentative ID so is left with a question mark for now.