The excipulum, the tissue making up the walls of the apothecium, is thin and flexible. The asci are produced in a cup-shaped structure called an apothecium. They are characterised by a cup-shaped apothecium which is often brightly coloured. The most common types of ascomata are the "apothecium" (plural&colon; apothecia) and "perithecium" (plural&colon; perithecia). The excipulum is the cup shaped tissue that holds the hymenium, asci, in the apothecium. The cup of the apothecium is lined with asci, in which the ascospores are contained. When moist, the cushion-like hymenial layer of the apothecium is golden-olive. The apothecium is described as being either sessile or immersed. The apothecium is raised slightly above the surrounding leaf tissue. In this stage, the sexual spores (ascospores) are formed in the apothecium. When the apothecium has an outer margin, the margin is called the "exciple". As the exposed apothecium matures, it changes from golden brown to dark brown in colour. The apothecium reproductive organ being unique to fungi but absent in other photosynthetic organisms. An apothecium is a wide, open, saucer-shaped or cup-shaped fruit body. During favorable environmental conditions (moist environment), the apothecium will produce asci typically containing eight ascospores.