Fragments of the Almahata Sitta meteorite has been found to contain tiny diamonds that indicate that it was once part of a large planet. Researchers suspect that these diamonds may have formed the same way diamonds do on Earth, in the unbelievably high temperatures and pressures of the interior of a planet. To create the right conditions, the meteorite’s parent body would have to have been a planet possibly as large as Mars.

Almahata Sitta belongs to a class of rocks known as ureilites, which are different than the rocks that come from modern planets. Unlike other meteorites, these rocks have no known source and seem to have been formed inside planetary bodies that no longer exist. One distinguishing feature of ureilites is they always contain tiny flecks of diamond, generally less than a fraction of a percentage of an inch in diameter.

A decade ago, an astronomer in Arizona discovered the asteroid on track to head straight for Earth. Reseachers tracked the asteroid as it entered Earth’s atmosphere and exploded in the sky 23 miles above the ground, with fragments falling on the Nubian desert in Sudan. Students from the University of Khartoum ultimately recovered more than 600 pieces of the meteorite.

A new study about the meteorite was recently published in the journal Nature Communications. Farhang Nabiei, a materials scientist at the Swiss Federal Institute of Technology in Lausanne, was the lead author of the new report.

Researchers found impurities trapped within the Almahata Sitta diamonds. To a geologist, the impurities trapped inside a diamond can be more precious than the diamond itself. Because of their strong crystal structure, diamonds can preserve microscopic bits of material that would otherwise disappear. The miniscule crystals of chromite, phosphate and iron-nickel-sulfide found within the Almahata Sitta diamonds are the first to have been discovered in an extraterrestrial diamond.

Researchers believe that the planet the meteorite came from was destroyed during the earliest days of the solar system, roughly 4.5 billion years ago. Nabiei thinks it’s likely that all ureilites come from the same parent body. Scientists still aren’t sure exactly where the parent body that broke apart into ureilites formed in the solar system, or how it was ultimately destroyed. There are still many other ureilite samples to examine and test to further the knowledge of what they are and where they may have come from.