A fossil galaxy sounds like the sort of thing Doctor Who would visit.

A tiny galaxy circling the Milky Way may be a fossil left over from the early universe, astronomers say. A recent study found that the stars in the galaxy, called Segue 1, contain fewer heavy elements than those of any other galaxy known, implying that the object may have stopped evolving almost 13 billion years ago. If true, Segue 1 could offer a window into the conditions of the early universe and reveal how some of the first galaxies came to be.

via RDFRS: Fossil Galaxy May Be One of First Ever Formed.