A slide labelled as Triceratium (which I believe is Triceratium robertsianum) from King George’s Sound. Single example on the slide. Prepared by Samuel Henry Meakin and mounted in Styrax. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 57 images stacked in Zerene (Pmax). Some really nice features which can also been seen in the video clip which shows the stage being moved.
Why do I think this is Triceratium robertsianum? Couple of reasons. It is mentioned in a USGS document for diatoms from King George’s Sound (see here). It also appears in Greville, R.K. (1863). Descriptions of new and rare diatoms. Series X. Quarterly Journal of Microscopical Science, Series 2 3: 227-237, pls IX, X, where it also appears to be a good match. It is described by Greville as ‘very rare’.