Diatoms are single-celled, photosynthetic eukaryotic algae, known as Bacillariophyceae, that are important in the ocean's cycle of nutrients and organic matter. There are possibly more than 150,000 varieties of them spread across fresh, brackish, and marine aquatic ecosystems, and they can be found in almost all aquatic habitats. Diatoms also have value to be used in industrial applications because their glass cell wall fossils are sold as diatomite or diatomaceous earth. Diatom silica, is regarded as an important usable biomaterial for energy storage e.g. (Lithium Ion battery, super capacitor, hydrogen and thermal storage ) and energy conversion e.g. (solar cells). In addition, diatomite exhibits substantial specified area of surface, thermal stability, and affordability, which provide tremendous benefits and prospects for application as filler in the paper, rubber, ceramic, pharmaceutical industries as well as abrasive material and soil amendment. In the field of water treatment, diatomite is considered as an eco-environmental functional material and effective adsorbent in the treatment of heavy metal-contaminated water because of its high porosity, low density and high specific surface area. In biomedical applications, mesoporous silica has recently demonstrated promising results in drug delivery systems because of its special chemical and physical characteristics, including excellent drug loading capacity, biocompatibility, and large surface area. Currently, basic and applied researchers are still interested in the use of diatoms in nanotechnology functions.