Final answer:
A star made purely of hydrogen and helium, if discovered, would likely be very old and would have formed in the early stages of the universe.
Step-by-step explanation:
Based on current theories, a star made purely of hydrogen and helium would likely be very old. These first-generation stars are believed to have formed in the early universe and have short lifespans, meaning they would have lived and died long ago. They would be found in very distant galaxies that formed when the universe was only a few hundred million years old. The light from these galaxies is only reaching Earth now, so observing these stars would provide valuable insight into the early stages of the universe.