Burl walnut is a type of wood that is harvested from the base of walnut trees, where a large ball often occurs. The burl itself is actually an abnormal growth or deformity on a walnut tree, often caused by some sort of stress such as a virus or bug infestation. When cut, this burled walnut has a distinct appearance that can be finished to create an attractive piece of furniture or other structure. Walnut burl wood exhibits a rich dark color with deep, complex grain patterns, and is often used in crafting high-end furniture, veneers, and decorative items.  In antique furniture, the use of burl wood ensures that each piece is distinctive whether used as the primary wood source or as a decorative veneer.