Why do people collect shark teeth?

If you don't know much about shark-tooth collecting, then you may not know that these relics are more than just teeth -- they're fossils. Sharks have been living on Earth for about 400 million years. When a shark dies and its cartilage dissolves, the teeth fall to the bottom of the ocean and get covered with sandy sediment. This sediment prevents oxygen and destructive bacteria from reaching the tooth, and it fossilizes over the course of about 10,000 years. That's why most of the teeth that are found and collected aren't white, but gray, black or brown -- the color of the sediment. The tooth absorbs the minerals in the sediment and these minerals eventually replace the dentine and enamel that makes up the tooth. Voila, you have a fossil on your hands.

Like all other fossils, shark's teeth can be valuable, so they're readily bought, sold and traded by enthusiasts and collectors. The most valuable of all is the tooth of the giant megalodon shark. This bad boy was a prehistoric beast that makes the modern great white look like your average goldfish. Great whites these days vary in size from 7 to 20 feet (2 to 6 meters). The prehistoric megalodon may have grown to a whopping 60 feet (18 meters).

The tooth of the megalodon ranges in size from 3.5 to 7 inches (89 to 177 mm) in length and can weigh more than a pound (.4 kg). Locating any megalodon tooth is a great find, and anything over 4 inches is rare and valuable. These teeth can go for as much as several thousand dollars each on the auction Web site eBay, depending on the size and the location where it was unearthed. The other factor that determines the value of the tooth is the shape that it's in. Even though teeth are fairly well ­preserved as fossils, they can be slightly eroded and contain chips and cracks from undersea rocks and coral.

So one reason people collect shark teeth is the shear monetary value. There are dozens of Internet sites devoted to the sale of these collectibles. Another reason is that on any given hunt, you may find a tooth from a giant, prehistoric predator that's 10 to 50 million years old. Most people would agree that digging up a 1-pound fossilized shark tooth as big as your hand is pretty cool. We'll give you some tips on the best way and best places to find these valuable fossils on the next page.

Sure, you can go online and buy a tooth from another collector -- and many enthusiasts do just that. But the most fun and rewarding way to do it is to get out into the water and find one with your bare hands. It can be as relaxing as a walk on the beach. In fact, there's not much more to it than that.

Low tide is the best time to find these sharp fossils. The water is calmer and clearer at low tide, giving you better visibility. The receding waters also expose some of the best areas to look for teeth. These areas are the drop-offs that occur just along the shore line -- where the surf goes back into sea, there's commonly a 6 to 12-inch drop in the sand level, called a "wash-in." Rocky sediment collects here and you can usually find a large amount of sea rocks, shells and, if you're lucky, shark teeth. Morning is a good time to search, if for no other reason than the fact that there are fewer people around to contend with.

Teeth can also be found on the beach itself, or even far away from the water. In fact, the inland town of Bakersfield, Calif., is known for producing some of the largest megalodon teeth ever found. After all, it used to be underwater, as did the entire state of Florida. Another tip when searching along the shoreline is to concentrate on areas where the sand is darker. It's also a good idea to head out after a storm. Ocean storms typically bring in all kinds of debris to deposit on the beach, including teeth.

You might want to carry along a small shovel, gardening pick and a sieve to sift through the sand -- and don't forget a bag to carry your booty. Once you have your teeth, you can check online or get a book to help you identify what kind of shark it came from. Then it's up to you exactly what you do with it. Avid collectors typically display the teeth in framed boxes, and many people include display cards indicating the species and the date and location where the tooth was found. Other people sell or trade with other collectors if the tooth is valuable. You can also make the tooth into jewelry if that's your thing -- shark tooth necklaces are a hot commodity among the Jimmy Buffett crowd.