When you consider these larger amounts, it is easy to understand how scientists estimate that more than 80% of the sand around tropical coral reefs is parrotfish poop!

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.

The Netflix documentary Chasing Coral makes passing reference to an extraordinary claim: Beaches are made of parrotfish poop. Here’s the thinking: These colorful beaked creatures of the reefs eat coral and grind up their calcium carbonate skeletons, which they then they poop it out as sand.

The sand on the right is 100% composed on shells, coral skeleton, and other biological precipitates.

17 Most Beautiful Islands in the World

1. Maldives. Maldives.
2. Bora Bora, French Polynesia. Bora Bora, French Polynesia.
3. Palawan, Philippines. Palawan, Philippines.
4. Seychelles. Seychelles.
5. Santorini, Greece. Santorini, Greece.
6. The Cook Islands. The Cook Islands.
7. Bali, Indonesia. Bali, Indonesia.
8. The Dalmatian Islands, Croatia. Zlatni Rat.

Parrotfish live in tropical waters near coral reefs. They eat algae that cling to the coral; pieces of coral pass through their digestive system and come out the other end as a fine, white sand. It is estimated that a single giant humphead parrotfish can poop out over 11,000 pounds of sand a year.

Often, underneath the loose sand of a beach is a layer of hard, compacted sand, which could be on its way to becoming sandstone if the necessary cement, pressure and heat ever appear — and if is not eroded by severe storms. These beaches commonly lose all the new sand in five years or so.

Short answer: Sand on beaches around the world comes from the weathering and pulverization of rocks over millions of years, along with fragments of shelled creatures and coral and that have been deposited on the coast by the waves.

Have you ever wondered if and how seashells are broken down in nature? None of the critters whose activities result in turning seashells into calcareous sand, or simply putting the calcium carbonate back into the ecosystem, are directly nourished by the seashells.

Old beach, new beach As a final sandy thought, consider the fact that the sand on most of our beaches, especially on the East and Gulf Coasts, is rather old: some 5,000 years or so, Williams said.

Sand grains travel southward down the coast, while finer particles of sediment are carried and deposited further out to sea. Along the way, sand is washed ashore, temporarily resting on beaches, until it is re-suspended in the ocean by wave action or wind.

According to a report on “Stand for Truth,” Ezekiel Galanto said mechanically placed sand can be washed out easily due to waves, tides, the current or wind.

“Most natural sand beaches are disappearing, partly due to rising sea levels and increased storm action, but also to massive erosion caused by development of the shore,” says Andrew Cooper, professor of coastal studies at the University of Ulster and co-author of The Last Beach.

Beach nourishment, or beach replenishment, is the practice of adding sand or sediment to beaches to combat erosion and increase beach width.

Beaches also attract tourists. It is a relatively inexpensive option but requires constant maintenance to replace the beach material as it is washed away.

Beach restoration involves the placement of sand on an eroded beach for the purposes of restoring it as a recreational beach and providing storm protection for upland properties. Rebuilding a natural beach is costly, and often ineffective.