Due to the heavy silica in diatom cell walls, dead cells tend to sink to the ocean floor, forming large deposits of diatomaceous earth that may be collected for industrial or paleontological uses. In a strict sense, diatomaceous earth should be considered fossil fuel because it is made up literally of millions of tiny preserved skeletons. Areolae are the secret to the success of old diatom tests in most of their industrial uses. This fine structure traps particles in fluids when used as a filter, or traps an insulating layer of air in terrestrial uses.

•  Used as a filter manufacturing of syrups, alcoholic and nonalcoholic drinks, medicines, solvents and chemicals.

•  Used as a filter in filler: paper, paint, ceramics, and detergent.

•  Used as insulation in high-temperature insulation, including fire doors; sound insulation.

•  Used as a mild abrasive in Metal polish and toothpaste.

•  Used for optical image quality measurements (some species, diatoms may be used to measure the resolving power and contrast of light microscopes)