"E. Coli", a glass sculpture by Luke Jerram
I think a lot of people assume that when you look at bacteria or viruses under a microscope, they're colorful. Mostly, they're not. Often they're clear.
Color loses it meaning for organisms that are are no bigger than a single wavelength of visible light, like E. Coli bacteria or smallpox viruses. The color seen in many biological images is there for one of two reasons: (1) because the technique used to image the microbe produces color (for example, fluorescence) or (2) because it's nicer to look at when color is added, either more aesthetically pleasing or just plain easier to see.
"Smallpox", "HIV", and "Unknown Future Mutation", by Luke Jerram
So Luke Jerram's blown glass microbiology sculptures, in addition to being timely, are that much more interesting because of their transparency.
Check out this great video of the process of making an HIV sculpture: