How to Find Fossils
Fossils are an excellent source of bells. You can dig them up and sell them. Most of them are worth a few thousand bells (many are worth over 4,500b). But how exactly do you find them? Well, if you’ve been playing the game for awhile, you already know that they are very common. You can dig them up just about anywhere, and anytime. You will see a small crack in the ground, just like everything else you can dig up. When you dig it up it looks like a blue colored rock with a white swirl on it.
What to Do With Fossils
If you don't want a fossil, you can go back to the hole and re-bury it. If you bring a fossil into your house before it has been identified, store it in a cabinet or drawer, not on the floor or a table because the Happy Room Academy regards these as trash.
Donate Fossils to the Museum
Take fossils to Blathers in your museum. When you talk to him, ask him to identify a fossil. He will take a look the fossil and then tell you what it is. If the museum needs it, he will ask you to donate it. You really should do this, because some are very rare, and when you eventually decide to fill the museum, you will wish that you had started it right away.
An interesting note about Blathers: On the GameCube version of Animal Crossing, you had to send off your fossils to the Farway museum for identification. Blathers said that he could not identify them officially, because he was still working on getting his certifications. Now, on City Folk, he must have his certifications for identifying fossils. It is so much more convenient to have them identified in your town's branch of the Farway museum!
Sell Fossils at Nook's
First, have Blathers identify your fossil. Now you can take your fossil to Tom Nook and he will buy it from you. Different fossils are worth different amounts of bells. For example, the most expensive fossil is the T.Rex. The tail pays 5,000b, the torso pays 5,500b, and the skull pays 6,000b. For a complete list of fossils and prices, buy the Prima offical guide to Animal Crossing.
Use Fossils as Decorations
You can also place identified fossils in your house, turning your house into a museum, but this takes up way too much space!