These are called "Marañón" in Spanish and they are used for a lot of different things. You can make jam and juice out of them or a form of liqueur called fenny. They are also sed in some Indian dishes. The fruit is very delicate and it can dye your clothes, so be careful.And one specific part of it is enjoyed by snackers all over the world.
The little brown piece at the end probably appears familiar. In this raw state it shouldn't be touched because it'shighly toxic and can cause rashes. The acid has to be cooked out and then it's safe to eat.
This tasty nut is a product of this strange, toxic fruit! Add a little heat to it and we have a delicious and healthy snack. Isn't nature wonderful?