A large percentage of the dazzling white sand on tourist packed beaches is actually parrot fish poop.
Sand making isn’t exactly a hobby for parrot fish, it’s simply a bi-product of their favored diet. A reef-dwellers equivalent to the accumulation of Doritos bags and Mountain Dew bottles that accumulates in the corners of college dorm rooms. Parrot fish subsist almost entirely on algae which lives in polyps tucked away inside coral bunkers. Lacking opposable thumbs, the fish use their beak-like jaw teeth to nip at this coral, breaking off small chunks and gulping them down whole. Once swallowed, they use specially adapted teeth within their throats to grind the coral into fine particles. The algae that accompanies these fine particles into the stomach are digested, and the particulate is excreted.
Enjoy making those castles!