Sordaria fimicola is a species of ascomycete that grows as a vase-shaped structure, or perithecium, on the excrement of plant-eating animals. According to a study by Thomas Volk (2007), Sordaria are a significant source for genetic studies because of its strict method of sexual reproduction, its quick reproduction due to its short life-span cycle, and its easy-to-see and distinct colors of ascospores. Their ascospores are spores produced within an ascus, and are born within a special fruiting structure called a perithecium. There are eight ascospores that are produced by two fusing nuclei within the ascus. The two nuclei fuse together to create a diploid nucleus that goes through meiosis and mitotic division to produce the eight ascospores. Perithecia are spherical chambers used for the production and releasing for ascospores. The asci in a perithecium are connected at their bases and form a layer of squished cylinders. Mycelium is a mass of branched filaments that are in the body of a fungus, and have cross-walls that are called the septa.
According to the Carolina Biological Supply Company (2005), the orders of ascospores in the ascus depend on the segregation of the chromosomes during meiosis. The wild-type gene produces a dark spore, and the mutant tan gene produces a light spore. Spores are small, single-celled asexual reproductive bodies that are produced by non-flowering plants and fungi. These genes produce a 4:4 sequence of ascospores if crossing over does not occur. They produce a 2:2:2:2 or 2:4:2 sequence if crossing over does occur and the genes do not segregate until meiosis II.