The large, round object in the center of this view is a diatom. Diatoms are protists that grow a silica shell around themselves. When diatoms divide, each offspring takes half of the original shell with it, and grows another matching half to complement the inherited shell portion. Diatoms are frequently found in wet environments, such as ponds. They also grow on most soil. Diatoms grow on the surface layer of soil, where they can use sunlight to produce food via photosynthesis. This species of diatom is yellow-brown in color when viewed with visible light. There are two basic types of diatoms: elongate ones and round ones, like this microbe. Elongated diatoms can move themselves about; round diatoms cannot. There may be as many as 10,000 species of diatoms. Huge accumulations of fossilized diatoms make up diatomaceous earth, which is used in toothpaste and in filters.