Diatomaceous earth is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It is made from the fossilized remains of diatoms, a type of hard-shelled microalgae. Diatomaceous earth is used in various industries, including agriculture, chemistry, and filtration. It is also used as an insecticide and pesticide, as it causes insects to dry out and die by absorbing the oils and fats from the cuticle of their exoskeleton. Some farmers add it to their livestock and poultry feed to prevent the caking of feed, and it is approved by the Food and Drug Administration as a feed additive to prevent caking. Diatomaceous earth is also used in industry as a filler or to prevent the formation of lumps in foods, medicine, paints, and plastics, and pet litter. It is used to clean up spills or for insulation in industry, as well as to scrub things. It is also used to remove unwanted material from drinking water.

There are two main types of diatomaceous earth: food grade, which is suitable for consumption, and filter grade, which is inedible but has many industrial uses. The diatoms in diatomaceous earth are largely made up of a chemical compound called silica. Silica is commonly found in nature as a component of everything from sand and rocks to plants and humans. However, diatomaceous earth is a concentrated source of silica, which makes it unique.