In Autumn 2007, a Tuscan father and son unearthed one of the largest white truffles ever found.
It later sold at auction for a record-breaking $330,000, more than six times the price of its weight in gold at the time.
Truffles are one of the world's most expensive foods, in part because global demand often outstrips supply.
But why are truffles so rare?
And why don't we just farm more of them?
The answers lie in the truffle's unique and somewhat mysterious biology.
Truffles refer to nearly 200 species of fungi, of which around 30 are used in commercial trade.
The most sought-after truffles are native to Europe, confined to regions with lime-rich dry soil and light summer rains.
Each species grows under the canopy of specific trees where they form tight, symbiotic relationships.
A truffle's mycelium, the vegetative root-like structure of the fungus, wraps itself around the tree roots and swaps water and nutrients for sugars.
