The term "epidurmos" seems to be a misspelling or a confusion with "epidermis," which is the outermost layer of skin in humans and many animals. The epidermis serves as a protective barrier against environmental factors, pathogens, and water loss. It is composed mainly of keratinocytes, which produce keratin, and also contains melanocytes, which produce the pigment melanin. If "epidurmos" refers to something specific outside of common terminology, please provide more context for clarification.