Humans harvest bird droppings for use as a

To most people, bird poop is just something they scrape off the windshield of their cars, but it's more important than we may think. ... This stinky substance, referred to as bird guano, was sailed around the world during the 19th century to be sold as the principal agricultural fertilizer in the United States.

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Kit ^w^

 sold as the principal agricultural fertilizer in the United States.

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indicate valleys, hills, steepness and gentleness of slopes.

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contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.

under a microscope, cancer cells may look very different from normal cells. they often have different sizes and some may be larger than normal while others are smaller. cancer cells are often abnormally shaped and the control centre of the cell (the nucleus) may have an abnormal appearance.

i think? ?