Sphagnum papillosum #5
Now here's where focus-stacking comes into its own, allowing such a three-dimensional shape such as this leaf, to be photographed with high DOF, without flattening it under a cover slip and taking advantage of the modelling effect of reflected light.
This is a synthetic image generated by focus-stacking 111 original frames taken through a compound microscope, with post-processing of the result using RawTherapee and Lightroom.
Update 20:43 BST: I've just rotated this 180 degrees in Flickr to orient the subject as it was on the microscope slide. The microscope inverts images and so the lighting in the previous orientation looked odd, being from bottom-left.
Have a look at a 3D rendering of this image stack.