Class Pyrenomycetes belongs to the Ascomycota phylum of fungi. This class is often referred to as "The Pyrenomycetes" or "The Pyrenomycetes Fungi." They are characterized by their fruiting bodies, known as perithecia, which contain asci (sac-like structures) that produce ascospores (sexual spores). Other synonyms for this class include "The Perithecial Fungi" and "The Ascomycetes Fungi," as they are closely related to other ascomycetes that also produce perithecia. Pyrenomycetes can be found in a variety of environments, such as soil, decaying wood, and plant debris, and they play important roles in nutrient cycling and decomposition processes.