Diatomaceous earth, often abbreviated as DE. is a fine grayish-white powder that comes from the long-dead remains of diatoms, a type of algae. It is mostly made up of silica, a very hard mineral, and it has a very coarse texture and absorbent properties. Diatomaceous earth has been used as pest control for thousands of years. You can even get food-grade DE that is safe for human or pet consumption. It has many health benefits.