Given a scientific passage and an answer, generate a question for the given answer.

Q: Passage: It's much easier to precisely make mirrors than to precisely make glass lenses. For that reason, reflectors can be made larger than refractors. Larger telescopes can collect more light. This means that they can study dimmer or more distant objects. The largest optical telescopes in the world today are reflectors. Telescopes can also be made to use both lenses and mirrors. Answer: destroyed

A: What happens to old oceanic crust at convergent boundaries?
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Q: Passage: The law of conservation of mass states that matter cannot be created or destroyed. Answer: destroyed

A: The law of conservation mass states that matter cannot be created or what?
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Q: Passage: Some of the most interesting kinds of evidence for evolution are body parts that have lost their use through evolution ( Figure below ). For example, most birds need their wings to fly. But the wings of an ostrich have lost their original use. Structures that have lost their use through evolution are called vestigial structures . They provide evidence for evolution because they suggest that an organism changed from using the structure to not using the structure, or using it for a different purpose. Answer: vestigial structures

A:
Structures that have lost their use through evolution are called _______
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