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Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
The average adult has about 21 square feet of skin.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Between 1999 and 2012, American adults with high total cholesterol decreased from 18.3% to 12.9%
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