Fresh Truffles are underground fungi that have a mycorrhizal relationship with the host tree where they grow. They flourish slightly beneath the surface of the earth, growing on the roots of different trees. Truffles are irresistible because their aroma is composed of chemicals that mimic mammalian reproductive pheromones. Eating, even sniffing a truffle brings about euphoric dizziness that can be truly addictive.
They are expensive because they are difficult to cultivate, hard to find in the wild, incredible to eat and in high demand. There are lots of species, but the two most sought-after are the powerfully flavourful Tuber Magnatum Pico, (the Italian white Alba truffle), and the Tuber Melanosporum Vitt. (the Périgord black truffle).