How does sand form?
Sand is the end product of many things, including decomposed rocks, organic by-products, and even parrotfish poop.
How does sand form?
Less common but no less inviting beaches, devoid of quartz as a source of sand, rely on an entirely different ecologic process. The famous white-sand beaches of Hawaii, for example, actually come from the poop of parrotfish. The fish bite and scrape algae off of rocks and dead corals with their parrot-like beaks, grind up the inedible calcium-carbonate reef material (made mostly of coral skeletons) in their guts, and then excrete it as sand. At the same time that it helps to maintain a diverse coral-reef ecosystem, parrotfish can produce hundreds of pounds of white sand each year!