A strew from the Baltic Sea, Kiel. Marine diatoms. Nice range of species. Prepared by Watson and Sons Ltd. Olympus BHB microscope using 450nm LED light. As well as the strew, I imaged one using the 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. 43 images stacked in Zerene (Pmax).
As for an ID of the one I imaged, I think this is Metascolioneis tumida (Brébisson ex Kützing) Blanco & Wetzel 2016. Published in: Blanco, S. & Wetzel, C.E. (2016). Replacement names for botanical taxa involving algal genera. Phytotaxa 266(3): 195-205. Page 200. Also known as Scolioneis tumida and Navicula tumida. Thanks to Anne Gleich for pointing me in the direction for this ID.