Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

600 million many years ago may the earliest fungi have evolved.
How many years ago may the earliest fungi have evolved?

Compound does the precise pattern of a crystal depend on.
What does the precise pattern of a crystal depend on?

Mechanical waves require a material medium such as water, air, or rope.

What waves require a material medium such as water, air, or rope?