The outer surface of a piece of flint.
The tissue of a stem or root that lies inward from the epidermis, but exterior to the vascular tissue.
The outer layer of an internal organ or body structure, such as the kidney or the brain.
An outer protective covering such as the feathers or skin of an animal, a rind or shell.
The outer layer of an ovule, which develops into the seed coat.
A shell or other outer protective layer.