Agaricostilbomycetes is a class of fungi within the phylum Basidiomycota, primarily known for its simple, often microscopic forms. Most members are yeasts or yeast-like fungi, though some produce small, delicate fruiting bodies with sterigmata-bearing basidia. They are characterized by having septal pores with dolipores and parenthesomes, and many species exist as saprotrophs, thriving on decaying plant matter, while others are associated with insects or plants. Although not as morphologically complex as larger mushrooms, they play an important ecological role in nutrient cycling and may also include species with potential biotechnological or agricultural applications.