One of these galaxies, among the most distant ever seen, appears to be unusually massive and mature for its place in the young universe. This came as a surprise to astronomers, as the earliest galaxies in the universe are commonly thought to have been much smaller associations of stars that gradually merged to build large galaxies like our Milky Way. The galaxy was pinpointed among approximately 10,000 others in a small patch of sky called the Hubble Ultra Deep Field (HUDF).