These don't look that exciting in "2-dimension", but if you can view cross-eyed stereo pairs they are fun to look at in stereo.
The empty tests were photographed "dry" sitting on a slide. They were taken with the Nikon MM-11 and the Olympus LMPLFLN 50/0.50. The first is reflected light. The second is brightfield, and the third is oblique brightfield (I was trying out a Zeiss Lucigen illuminator fitted to the stage I use with that microscope).
The test in the first two images measures 342 microns (0.013") and the last one is a little smaller at 225 microns (0.0088").
Images made through a microscope. All subject types.