Actually the seed of a giant tree that grows in South America's Amazon jungle. These seeds come in clusters of 8 to 24 inside a hard, 4- to 6-inch globular pod that resembles a coconut. The extremely hard shell of each seed, or "nut," is dark brown and triangular in shape. The kernel is white, rich and high in fat. Brazil nuts are rich in selenium, a powerful antioxidant. See also nuts.