Some estimates put the first human settlements in the Amazon at 32,000 to 39,000 years ago. Since that time, Amazon people have developed lifestyles that are well integrated with the benefits and constraints of rainforests.
An estimated 7-10 million Amerindians (the term for American Indigenous peoples) lived in American rainforests, half of them in Brazil, at the time of European arrival. When Pizarro arrived in Peru, more land was under cultivation and more food was being produced in the Andean region than today.
There's actually an entire documentary made about this certain fish, its name is Parrot Fish.
The reason for its name is because it has a beak, which it uses to bite and eat through coral.
And at the end of the day, when the fishes poop, it turns into sand.
For example, one 2010 study in Marine Biology found that large parrotfish in Hawaii can churn out 840 pounds of eroded coral—i.e. white sand—per year. A single giant humphead parrotfish can produce 11,000 pounds of sand per year.
hope this helps!