Environmentalist Rachel Carson wrote, “There is a story about the earth on every curved beach and in every grain of sand.” When decomposed by erosion, sand is formed. It takes time for rocks to break down, especially quartz and feldspar.
Rocks usually start from the ocean thousands of kilometers away, slowly moving down rivers and streams, and constantly breaking down on the way. Once they enter the ocean, they are constantly eroded by waves and tides.
However, biological by-products also play an important role in the process of forming beaches. The advantage of Bermuda’s charming pink beach comes from the permanent decay of a single-celled, shelled creature called foraminifera. And scientists have proven that about 70% of the sand on tropical beaches is actually the faeces of parrotfish. For example, the famous white sand beaches of Hawaii actually come from the faeces of parrotfish.
This fish uses a parrot-like beak to bite and scrape algae from rocks and dead coral, grind inedible calcium carbonate reef material (mainly made of coral skeletons) in the intestine, and excrete it as sand. While helping to maintain a diverse coral reef ecosystem, parrotfish can produce hundreds of kilograms of white sand each year.