BBC.CNN WORLD NEWS

Did you know that you now have 96 fewer bones in your body than when you were born? There's a lot more you never knew to ask. Check to see how many of these facts you knew:

    * If you remove the minerals from a bone by soaking it overnight in a six percent solution of hydrochloric acid, it will become so soft, you could tie it in a knot.
    * One person in 20 has an extra rib, and they are most often men.
    * When you were born, you had 300 bones. Now you have 206, if you are an adult. The rest of the bones have not disappeared – they have merely fused together.
    * The female egg cell is the largest cell in the human body. It is about 175 000 times heavier than the smallest cell, the male sperm cell.
    * There are 96 000 km of blood vessels in the average adult body.
    * The average person has about 100 000 scalp hairs.
    * When you look at an object, the image of that object appears upside down on your retina. However, your brain automatically corrects for this, allowing you to perceive the object the right side up.
    * Enamel, found on our teeth, is the hardest substance in the human body.
    * The soles of your feet contain more sweat glands and more pressure-sensitive nerve endings per square inch than any other part of your body.
    * Like fingerprints, every person has a unique tongue print.
    * The kidneys filter your blood up to 300 times per day.
    * During the first six weeks of life, there is no difference between the male and female embryo.
    * Human fingers stretch and bend about 25 million times in a normal lifetime.
    * The human body contains 30 000 billion red blood cells.
    * Tooth decay has led to 60 percent of adult Americans losing their upper right, middle molar.