 Derived from the Greek word peridion, meaning "small leather pouch", the peridiole is the "egg" of the bird's nest. It is a mass of basidiospores and glebal tissue enclosed by a hard and waxy outer shell. The shape may be described as lenticular — like a biconvex lens — and depending on the species, may range in color from whitish to grayish to black. The interior chamber of the peridiole contains a hymenium that is made of basidia, sterile (non-reproductive) structures, and spores. In young, freshly opened fruit bodies, the peridioles lie in a clear gelatinous substance which soon dries.
