The white stuff that is sometimes seen at the root of hair is called the hair bulb or hair follicle. It is a part of the hair structure that surrounds the base of the hair shaft and is located below the surface of the skin. The hair bulb contains cells that divide rapidly, allowing for the growth of new hair fibers. It also contains melanocytes, which produce the pigment that gives hair its color.
The white appearance of the hair bulb may be due to the accumulation of sebum, a natural oil produced by the skin, or dead skin cells.