The torn peridium exposes the internal gleba. The ruptured peridium remains as a loose volva at the base of the stalk. The inner peridium is a spore sac. The network of fertile tissue inside the inner peridium, the capillitium, arises from the columella. The peridium (outer wall) consists of several layers, including a gelatinous layer. In some species, the inner peridium is borne on a stalk or pedicel. The peridium is the protective layer that encloses a mass of spores in fungi. For example, the peridium of the sub-family Phalloideae is called a volva. Spores are released when the peridium eventually splits open into irregularly shaped sections. They are surrounded by a membrane called a peridium that bursts, releasing the spores. For most fungi, the peridium is ornamented with scales or spines. It has a two-layered peridium. All species have a caeoma which is a diffuse aecidium lacking a peridium. The exoperidium flakes off in maturity to reveal a thin, inner peridium (endoperidium). The peridium, which consists of six distinct layers, forms two "cups" at maturity.