Photo: M Swiet Productions/Getty Images

Do you really want to know?

Everyone loves gorgeous, smooth, soft, white sand beaches, right? They pair beautifully with sparkling waves and a clear sky, and they make the perfect setting for a delightful day under the sun. On any given weekend, tropical beaches across the globe have happy visitors strolling along them, searching for shells, or just enjoying the stunning vista.

What many of these beach-goers don’t realize, though, is that some of these beaches are—at least in part—made of fish poop.

Yes, fish poop.

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Before you cancel your beach trip, read on: It’s not as gross as you think. Tropical islands (and their sugary sand beaches) are often surrounded by flourishing coral reefs, where colorful parrotfish live. Parrotfish eat the algae that grow on coral. If you’ve ever snorkeled near a reef, you’ve probably seen them nibbling on coral in search of their food. (This is good for the reefs, when kept in check, as it prevents the algae from smothering them.)

 Photo: Wild Horizon/Contributor/Getty Images

Parrotfish’s large, beak-like teeth (which inspire their name) help them break off and eat small pieces of coral. They have another set of teeth, called pharyngeal teeth, at the backs of their throats. These secondary teeth grind up the coral into small grains of sediment, which parrotfish then excrete in clouds of white powdery sand. (A single large parrotfish can produce hundreds of pounds of sand a year!) The sediment is distributed onto the reef and, eventually, can pile up above the surface of the water, forming islands like the Maldives and other white sand beaches we know and love. Parrotfish's prolific production of sand—with the help of other sea creatures—also maintains the sandy beaches on islands around the world.

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Not all white sand beaches are composed of parrotfish's handiwork—many of Florida's white sand beaches are made of ground-up quartz, for example. But if you're in an area with flourishing tropical coral reefs, there's a good chance much of your beach is comprised of fish poop. Scientists suspect much of the Maldives’s coral reef islands were made by this process, and many of the white sand beaches of Hawaii and the Caribbean are largely made of parrotfish poop. Mahalo, parrotfish!

What do you think? Gross, or just more evidence of how amazing nature is?

(h/t Wired)

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