Toronto. I took this shot in October 2014 with a century old Zeiss licensed, Krauss made Tessar 35mm f/3.5 at f/22 after looking at the soil sample under a Leitz stereo microscope using 12.5x, 50x, and 100x magnification. The Tessar shot is about 25x magnification before any computer screen enlargement. According to the web, the tiny ball is either a slug or snail egg. Scott’s (the seed and fertilizer people) say it is a slow release fertilizer bead. I tend to agree with Scott’s.
The tiny 35mm f/3.5 Tessar lens has an RMS (Royal Microscopal Society) thread (a standard once used by all microscope makers). I used a Leitz RMS to 39mm adapter, Leitz Bellows II, Visoflex housing II, Leitz M-mount to Sony E-mount adapter and my Sony NEX-6 camera to make this image.
Just as a note, in the early years of photography, Zeiss licensed other camera lens makers to use their lens designs. Licensing over-came duty penalties, scarce resources in house, and spread the name and prestige of Zeiss designs world wide.