Sinnie Bernal, a primordial dwarf, and her sister Sierra, may be the most unique twins you'll ever see.
From the abcnews.go.com
Sierra is an average-size girl, which makes the twins the only known pair in the world in which one is average size and one is a primordial dwarf.
From the abcnews.go.com
The near absence of such heavy elements suggests that much of the primordial gas in the dwarf galaxy has not managed to form stars that subsequently manufacture heavy elements.