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The average adult has about 21 square feet of skin.
If you could remove all of your skin, it would weigh up to 5 pounds.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.
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