Astronomers recently discovered a 13-billion-year-old galaxy cluster that is the earliest ever observed. According to a paper released Friday, this finding may hold clues about how the universe developed.

Such an early-stage cluster — called a protocluster — is “not easy to find”. Yuichi Harikane said this in a press release. He is a researcher at the National Astronomical Observatory of Japan who led the international team.

“A protocluster is a rare and special system with an extremely high density,” Harikane said. He added that the researchers used the wide viewing field of the Subaru telescope in Hawaii to “map a large area of the sky” in their search.

The discovery of the protocluster, a collection of 12 galaxies, suggests that large cosmic structures were present in the very early stages of the universe. Scientists also believe was the universe was born 13.8 billion years ago.

Himiko is one of the 12 galaxies. Scientists found the giant gas cloud in 2009 by using the same telescope.

“It is reasonable to find a protocluster near a massive object, such as Himiko. However, we’re surprised to see that Himiko was located… on the edge 500 million light-years away from the centre,” the paper’s co-author Masami Ouchi said.

However, he said they do not yet understand why Himiko is not located in the centre. “These results will be key for understanding the relationship between clusters and massive galaxies.”

The team included scientists from Imperial College London and they published the study in Friday’s Astrophysical Journal.