A strew slide from Cormack’s [Siding], Oamaru, New Zealand. Fossil material. Nice range of species including lots of fragments of Brightwellia sp.. Mounted in Zrax. Prepared by D. Prades. Olympus BHB microscope using 450nm LED light. I selected one which looked different, but unfortunately it was very closer to the coverslip ring. However I was still able to use the 63x Leitz Pl Apo NA 1.40 oil immersion objective. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 34 images stacked in Zerene (Pmax).
I think this could be Pleurosira laevis. It certainly looks like it. However I have so far not been able to find reference of this being found in the Oamaru deposits. It is rim upwards towards the coverslip (an underside view). A bit of a mystery this one, and I will leave the name with a question mark for now.
I also found a piece of what I think could well be a diatom girdle. Amazingly regular structure.