Truffles are a subterranean type of edible fungi that grow under the ground inconspicuously. That property has always made them mysterious and unknown, but nowadays it contributes to the perception of truffles as something enigmatic and difficult to obtain. They resemble tubers with a round or irregular shape. They have a rind, which is relatively smooth in the Istrian white truffle and lumpy in the black truffle. 

Depending on the species, the flesh may be white, yellowish-white, light brown, dark brown, brownish-grey, brownish-purple, reddish and black. The colour of the flesh also varies and depends on the tree host the truffle lives in symbiosis with. Whether the truffle is criss-crossed with veins, which may be narrower or wider, also depends on the species and also on the habitat.