Coscinodiscus angulosus from Conset, Barbados. Single example on the slide. Prepared by RI Firth. Olympus BHB microscope using 450nm LED light. 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. 38 images stacked in Zerene (Pmax). Got a bit lucky with this one with regards to stacking. I just managed to get to the based of the diatom when the objective came into contact with the slide.
Coscinodiscus angulosus J.W.Barker & S.H.Meakin, 1946. Published in: Barker, J.W. & Meakin, S.H. (1946). New and rare diatoms. Journal of the Quekett Microscopical Club Series 4, 2(2): 76-79, pls 15,16. Page 76, Plate 15, Figure 3. Described as ‘Conset, Barbados, Very rare.’.
I think this is also described as Triceratium groningensis Reinhold (1937). See Fenner, J., 1978. Cenozoic diatom biostratigraphy of the equatorial and southern Atlantic Ocean. In Perch-Nielsen, K., Supko, P.R., et al., Init. Repts. DSDP, 39 (Suppl., Pt. 2): Washington (U.S. Govt. Printing Office), 491–624. Page 545, Plate 28, Figures 1,2. Original description: Reinhold, T. (1937). Fossil Diatoms of the Neogene of Java and their Zonal Distribution. Verhandelingen van het Geologisch-Mijnbouwkindig Genootschap voor nederland Kolonien, Geol. Serie, 12: 43-133; 21 pls. Page 126, Plate 20, Figure 9.
For another example of it on this site, see here.