The Parrotfish eats dead coral, an then poops sand. This sand poop is also responsible for nearly all the white sand beaches in Hawaii

Sand comes in many different colors, sizes and even shapes if you look close enough. It would be hard to have it all the same with an estimated seven quintillion, five hundred quadrillion grains of sand in the world.

Many beaches around the world are known for their beautiful sand. Hawaii, for example, is consistently ranked among the top beaches in the world for its pristine, white sand. But this sand has an origin that might make you think twice about stepping onto one of those beaches.

The white sand of Hawaii is made up primarily of poop. That would be the poop of parrotfish. These fish bite off coral and grind it down into sand with their teeth. They don’t have stomachs, so it passes straight through them and out the other end as sand.

Larger parrotfish are like sand factories, producing as much as 840 pounds of sand per year. For Oahu’s snorkeling hot spot, Hanauma Bay where a few hundred parrotfish graze, that means hundreds of tons of fish-made sand per year.

Parrotfish aren’t the only creatures to poop sand, but they are the most proficient. Worms, sponges, and oysters also produce Pacific ocean sand.

(Source)