Astronomers have discovered what could be a rare fossil relic of the early Milky Way. Terzan 5, which has been classified as a globular cluster, is 19,000 light years away from Earth and located in the Sagittarius constellation. The star cluster could provide a more detailed look into the early days of the universe.

According to the European Southern Observatory, two distinct kinds of stars were found in Terzan 5, which differ both in the elements they contain and their age gap. The two populations are approximately 7 billion years apart and the ages indicate that the formation process was not continuous.

The data was partly gathered from the Very Large Telescope, as well as from NASA’s Hubble Space Telescope. Terzan 5 was originally discovered 40 years ago but astronomers now have been able to confirm the stars vary in composition and age, with the oldest population measuring in at 12 billion years old.

The findings, which were published in the Astrophysical Journal, suggest that Terzan 5 could be “a living fossil from the early days of the Milky Way.” This discovery could represent an early building block of the Milky Way, with properties to that of the Milky Way’s galactic bulge, or central region.

Francesco Ferraro, of the University of Bologna, Italy, and lead author of the study, said in the news release, “Such galactic fossils allow astronomers to reconstruct an important piece of the history of our Milky Way.” According to Ferraro, Terzan 5 could provide a crucial link between the local and distant universe.

Going forward, this discovery could pave the way for a better understanding of galaxy formation and the “evolution of spheroids and their stellar content.” The findings could provide key insights for astronomers into the early days of galaxy formation, which still largely remains a mystery. The characteristics of the fossil relic could also provide further clarity into the Milky Way’s complex history.