Tulane University defines an ore as a body of material from which one or more valuable substances can be extracted. For example, bauxite ore is mined and refined to extract aluminum.
root sheath the epidermic layer of a hair follicle. sheath of Schwann neurilemma. synovial sheath synovial membrane lining the cavity of a bone through which a tendon moves. tendon sheath a lubricated fibrous or synovial layer of tissue in which the tendon is housed and through which it moves.
A root hair is a simple extension of the epidermis of a root cell, and reach into the soil to absorb water. It exists to increase the surface area and therefore the rate at which water can be absorbed. Some plants have fungi which act like fine roots, absorbing nutrients from the soil for the plant.