Write a correct answer to the given question based on its associated fact. Make sure that your answer is contained in the associated fact. Don't be creative and introduce any new word that is not mentioned in the associated fact! Remember that the associated fact has been rearranged to form the question. So, the correct answer words must lie within the associated fact. The correct answer can be a word, phrase, or even a sentence.

Q: Fact: animals with calcite shells form large colonies in shallow tropical water. 
Question: Animals with _ form large colonies in shallow tropical water?

A: calcite shells.
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Q: Fact: nails prevent water loss. 
Question: what do nails prevent?

A: water loss.
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Q: Fact: Some animals' hair grows thicker for staying warm in the winter. 
Question: Why do some animals have hair that grows longer during the winter?

A:
to stay warm.
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