Diatomite (also called diatomaceous earth) is a white- or cream-colored, friable, porous rock composed of the fossil remains of diatoms (small water plants with silica cell walls). These fossils build up on the ocean bottoms to form diatomite, and in some places these areas have become dry land or diatomacceous earth. Chemically inert and having a rough texture and other unusual physical properties, it is suitable for many scientific and industrial purposes, including use as a filtering agent; building material; heat, cold, and sound insulator; catalyst carrier; filler absorbent; abrasive; and ingredient in pharmaceutical preparations. Dynamite is made from it by soaking it in the liquid explosive nitroglycerin.