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Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
Blood is approximately twice as thick as water because of the cells and other components found in it.
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.
Today, nearly 8 out of 10 pregnant women living with HIV (about 1.1 million), receive antiretrovirals.
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.