This is labelled as Aulacodiscus bermudensis, fossil marine from a Bermuda Rise core. 3 examples on the slide. The 5 point one is 204µm, the 6 point one is 174µm and the 7 point one is 241µm. Prepared by ECP Bone. Mounted in Styrax and dated December 1977. This is a little bit of a mystery as I couldn’t find mention of A. bermudensis or examples to compare against. I’ve been told by an expert that this could be a variation of Aulacodiscus amoenus. Olympus BHB microscope using 450nm LED light. 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, brightfield lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 23 images stacked in Zerene (Pmax).