Xylobolus frustulatus, commonly known as the ceramic fungus or ceramic parchment, is an inedible species of crust fungus in the Stereaceae family. The fruit body forms small, hard, flat crust-like aggregations that resemble broken pieces of ceramic tile. These pieces are initially whitish before turning yellow-brown to gray-brown in age. The spore-bearing cells cover the upper surfaces of the fruit body. A saprobic species, it grows on well-decayed oak wood in Asia, northern Europe, and North America.