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: Mesoderm type of cell layer do flatworms have.

Answer: What type of cell layer do flatworms have?


Question: Pangaea began breaking apart 250 million years ago.

Answer: How many millions of years ago did pangaea begin breaking apart?


Question: Nonvascular plants reproduce with spores.

Answer:
What do nonvascular plants reproduce with?