The Brazil nut is the seed of a tall South American tree of the species Bertholletia excelsa. The individual seeds are shaped something like citrus segments, and grow in clusters surrounded by a thick husk like that of a coconut. Since the tree will only bear fruit when pollinated by certain local species of bee, all commercially-available Brazil nuts are harvested from the wild rather than cultivated.

The fact that they are wild-harvested makes the nuts fairly expensive, such that they have limited culinary use in themselves. Instead, they are often used sparingly in mixed-nut assortments, with cheaper ingredients such as peanuts and almonds filling out the bulk of the mix. They are also commonly available unshelled, in which form they carry a deserved reputation as the proverbial toughest nut to crack. In recipes, they are a good substitute for more costly macadamia nuts.