Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Some meteorites are made of iron and nickel and are thought to be very similar to the core of the earth.

Answer: Some meteorites are made of iron and nickel and are thought to be very similar to what part of the earth?


Question: The water in some springs are hot because they're heated by hot magma.

Answer: The water in some springs are hot because they're heated by what?


Question: Fertility does the color of soil indicate.

Answer:
What does the color of soil indicate?