This image shows a collection of diatoms at a magnification of 200. Diatoms are aquatic, photosynthetic protists and are one of the simplest forms of phytoplankton. They are abundant in nearly every habitat where water is found – oceans, lakes, streams, mosses, soils and even the bark of trees. Nearly all diatoms are microscopic; cells range in size from about 2 microns to about 500 microns (0.5 mm), or about the width of a human hair.
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