Aluminium coated Pleurosigma angulatum strew slide by Horace Dall. The aluminium coating makes for a dark ground looking image when viewed from below in standard brightfield conditions. Olympus BHB microscope using 365nm LED lighting. Nikon 40x UV-F NA 1.4 objective with glycerine immersion. Olympus Abbe condenser with glycerine immersion, one side blocked to give slightly oblique lighting. Monochrome converted Nikon d800 camera. Nikon 5x CF photoeyepiece. 8 images stacked in Zerene (Dmap).