Close to two decades after it was first discovered, it was announced in 2013 that the so-called Hypatia stone was of extraterrestrial origins. Years later, scientists discovered that it did not come from any previously discovered comet or meteorite, as its makeup did not match that of any known objects from our solar system. Now, it looks like there are finally some new theories regarding the stone’s unusual makeup, and these theories could contradict what we know about the materials that made up our solar system when it was formed.

Although the researchers published their findings on the Hypatia stone toward the end of 2017, it was only this week when the study, which was posted in the journal Geochimica et Cosmochimica Acta, began to get attention for the researchers’ unusual explanation behind the pebble’s structure. According to lead researcher Jan Kramers of the University of Johannesburg, Hypatia is reminiscent of a fruitcake that had broken into several pieces after falling off a shelf.

“We can think of the badly mixed dough of a fruitcake representing the bulk of the Hypatia pebble, what we called two mixed ‘matrices’ in geology terms,” said Kramers.

“The glace cherries and nuts in the cake represent the mineral grains found in Hypatia ‘inclusions’. And the flour dusting the cracks of the fallen cake represent the ‘secondary materials’ we found in the fractures in Hypatia, which are from Earth.”

Phys.org explained that the larger rock which the Hypatia stone came from might have had a diameter of at least “several meters,” before it broke into smaller pieces when it crashed down to Earth.

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Extraterrestrial space rock Hypatia predating the formation of the solar system? #space — Cosmological (@kenserlore96) January 10, 2018

According to Newsweek, the Hypatia stone was first discovered in 1996, and was named after an ancient Egyptian female mathematician and astronomer. Its peculiar features mystified scientists to the point that it took 17 years before they confirmed that the stone did not come from Earth, but the origin of those features remained a mystery in the years that followed. Science Alert wrote that theories on the stone’s makeup had varied, including one that suggested it could have come from a comet’s nucleus, and another that suggested it was created in a cold molecular cloud.

Based on the new study’s findings, the Hypatia stone’s “super-hard, but brittle and fractured” texture and “strange” shining qualities could be explained by its similarly unusual blend of materials, Newsweek added. While most meteorites are mostly made up of silicon, with a smattering of carbon content, Hypatia is the opposite, as it’s rich in carbon with a little silicon mixed in, with a good percentage of the carbon in the stone seemingly transformed into tiny diamonds due to the shock of impact with Earth’s atmosphere or surface.

“Even more unusual, the matrix [of materials that make up Hypatia] contains a high amount of very specific carbon compounds, called polyaromatic hydrocarbons, or PAH, a major component of interstellar dust, which existed even before our solar system was formed. Interstellar dust is also found in comets and meteorites that have not been heated up for a prolonged period in their history,” Kramers noted.

Adding to the peculiarity of the Hypatia stone’s makeup is the presence of various metals, including pure aluminum, within the aforementioned blend of carbon and silicon. Study co-author Georgy Belyanin, also from the University of Johannesburg, called this an “extremely rare” occurrence on Earth and other parts of our solar system.

Given the unlikely inclusion of metal chunks in the Hypatia stone, the researchers believe that the metal represents small parts of the solar system before it was actually formed. This could suggest that various elements were scattered randomly around our solar system while it was forming, instead of being spread out evenly. It’s also possible that the rock Hypatia originated from might have come from as far back as the Kuiper belt, which is 40 times farther away from the sun as Earth is, or the Oort Cloud, which, as Newsweek pointed out, engulfs our entire solar system.

Regardless of where the Hypatia stone actually came from, the researchers stressed that more research may be needed to answer the many new questions that sprung up about its origins after their findings were published.