Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[EX Q]: Question: What is the structure which hangs from a newly hatched salmon larva? Answer: yolk sac
[EX A]: Salmon Larva. This newly hatched salmon larva doesn't look very fish-like. The structure hanging from the larva is the yolk sac.

[EX Q]: Question: What is lava called before it reaches the surface of the earth? Answer: magma
[EX A]: Minerals form as magma or lava cools.

[EX Q]: Question: What occurs when air masses meet? Answer: fronts
[EX A]:
Much of the weather occurs at fronts, where air masses meet.