Coloring pictures is an educational exercise, which is fun, and helps develop important skills. Coloring SEM micrographs is especially suitable for electron microscopists. Color micrographs are not just great looking on a lab wall; they inspire both microscopists and students to exercise digital picture manipulation. Many microscopists enjoyed looking at the beautiful color micrographs by D. Scharf, but were frustrated to learn they needed a very particular scanning electron microscope equipped with multiple secondary electron detectors in order to color their own pictures. Fortunately, there are other ways to color SEM micrographs. Most SEMs are equipped with at least two detectors, for secondary and backscattered electrons.

As part of our introductory Cell Biology course, our students acquire images through microscopes using consumer cameras with memory cards. They then transfer the images to a computer and prepare them using Adobe Photoshop Elements.™ An important part of this process is learning to apply a scale bar, which calibrates the specimen image. Photoshop Elements is a relatively cheap and widely available software package that easily accomplishes this task for anyone who is using a camera system or software that does not automatically apply a scale bar or calibration data to the image. The instructions and figures herein refer to Photoshop Elements version 4.0, but they apply to other versions of the software.

Tiny (50-200 nm) spheroids were first discovered by Folk through SEM work on the hot springs of Viterbo Italy. He termed these small, spherical structures “nannobacteria,” and proposed that they may be important agents in precipitation of CaCO3, as needle-like crystals of the mineral aragonite, and as bundles of such needle-like crystals (termed “fuzzy dumbbells”), or as elongated crystals of the mineral calcite.

During the past 15 years, nanometer-scale spheroids have been discovered in the geological, medical, and astronomical worlds. There can be no doubt as to their existence, but their significance and origin remain a subject of continuing controversy. Even the spelling (“nanno-“), which has been the standard in biology, geology, and paleontology going back to the 19th century, has been questioned. Whether or not they are truly bacteria or any form of life has been a subject of heated debate.