THE OLDEST KNOWN PIECE OF EARTH

According to a news article on cnn, scientists have found the oldest object on earth. Its a zircon crystal with the diameter of a human hair. They say it's 4.4 billion years old. Really?This little gem of information should be enough to tax the common sense of even the most gullable of idiots. First of all, how do you go about finding the one oldest thing on earth when it's only the diameter of a human hair. Then how do you go about finding out that it's 4.4 billion years old. That means they're saying it's 4.4 thousand million years old. It seems to me that it would be very easy to be out by a million years or so.