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Hairs on a skin mole. Coloured scanning electron micrograph (SEM) of hair growing from follicles in the skin of a human mole or birthmark. Hair is made up of a fibrous protein called keratin. The outer layer of the skin, the stratum corneum, consists of dead keratinized cells that detach from the body giving a flaky appearance. As skin cells die and detach, more cells are produced from the epidermis below. Skin cells in moles or birthmarks are more heavily pigmented with melanin than other skin cells. Magnification: x240 when printed 10cm wide. (KEYSTONE/SCIENCE PHOTO LIBRARY/EYE OF SCIENCE)