Microscopic

Photographed slides under magnification.

Edit: I was asked to describe the viruses and bacteria shown, and upon looking at the original photos I realized that there's some fungus and protozoa in there too.
Starting at the top left is Zygomycota Rhizopus (fungus) spp., followed by Ascomycota Saccharomyces (fungi) spp. and Ciliophora Paramecium (protozoa) spp..
In the next row are Chlorophyta Volvox sp., Chlorophyta Spirogyra spp. (both algae), and another slide of Rhizopus.
The third row begins with Cyanobacteria Osillatoria spp., followed by Chlorophyta Hydrodictyon (again both algae). I'm not sure about the purple one next to it.
The last row begins with yet another example of Rhizopus (aka bread mold) and is followed by a slide of assorted bacteria, and lastly a slide of Cyanobacteria Nostoc spp.
Correct me if you find discrepancies! Anyway, this is just a little slice of what's really out there and was originally intended for study use. Specimen provided by the University of Northern Iowa, McCollum Science Hall.

(The abbreviation "sp." represents a single organism of that species, and "spp." denotes that multiple organisms of the species are present on the slide.)