This exceptional subterranean fungus grows to a size varying from that of a walnut to as large as an apple.

At least two species are found in the woods of the "Sagrantino Road": the more valuable species, the black winter truffle (Tuber melanosporum), matures from November to March in the vicinity of oaks, hornbeams, hazelnuts, ilexes and rockroses, and has a black or blackish skin, which is wrinkly but does not have the coarseness of other species with a blackish skin. Its pulp is a purplish-black color, with thin veins of white that turn reddish-brown at the sides. This species grows in soils that are crumbly or calcareous, pebbly, tending to be arid, at elevations from about 250 to 1000 meters above sea level. The other species found is the black summer truffle (Tuber aestivum), which matures from May to August, in symbiosis with broadleaf trees or some types of conifer. It has a black, very coarse skin and is brownish-white inside.