Have you ever been to a really fancy restaurant? We're not talking about the kind of place that has a drive-through window! Instead, we're talking about the kind of place that has linen tablecloths, fine china, and servers in tuxedos!

If you've ever been to such a fine dining establishment, you might have been amazed by the types of food on the menu. Rather than French fries and hamburgers, you probably read descriptions of dishes like foie gras and caviar. You might have even been able to order a dish featuring one of the most expensive foods on Earth. What are we talking about? Truffles, of course!

No, not the chocolate truffles you might see lining store shelves around Valentine's Day. We're talking about the rare edible fungus that grows underground, usually at the base of certain types of trees. Similar to mushrooms, truffles can look a bit like potatoes. They feature a distinctive aroma and taste that chefs around the world crave.

Unlike most other types of food, truffles can't really be planted or grown commercially. They can't be concocted in a laboratory or raised in a greenhouse. Truffles only grow in certain areas under very specific conditions.

In fact, they usually only grow when partnered with certain trees, including oak, hazel, poplar, beech, and pine trees. The tree roots provide needed sugars to help the truffles grow and, in return, the truffles provide certain nutrients to the tree.

Many people try to grow truffles by planting certain types of trees in limestone soil in the right climate. The rest, however, is up to Mother Nature. Today, most truffles are harvested in the wild from areas in France, Italy, China, and Croatia, although some areas of the Pacific Northwest in the United States have produced truffles, too.

As if they weren't rare enough to begin with, truffles can be hard to find since they tend to grow a foot or more underground. Luckily, their pungent aroma can be sniffed out by specially-trained pigs and dogs. Pigs happen to love truffles, so truffle hunters using pigs must be quick to grab truffles before the pigs can eat them. For this reason, many truffle hunters now prefer to use dogs, since they don't seem to care for truffles all that much.

There are several different types of truffles. The French black, or Périgord, truffle can be found in southwestern France. It is known for its aroma and can weigh two pounds or more. The Italian white, or Piedmont, truffle can be found in northwestern Italy and is extremely rare. It has the strongest aroma of all truffles and can weigh as much as one pound.

Chefs who love truffles usually shave or slice them raw over dishes, including pastas, rice, salads, eggs, and meats. They can also be infused into sauces, soups, cheese, butters, and oils.

Because truffles are so rare, yet so sought after by the world's chefs, they can be extremely expensive. The cheapest truffles can cost $100 or more per pound. And those white Piedmont truffles from Italy? Those rare fungi can command prices of several thousand dollars per pound! Recently, a charity auction sold a pair of rare white truffles, one of which weighed about two pounds, for a whopping $330,000!

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