Markings found on an ancient Indonesian shell could be the earliest engraving from a human ancestor, according to a new study. The study indicates that the engraving, which features zig-zag patterns, is at least 430,000 years old. The age of the shell suggests that it was carved by Homo erectus, a long-extinct species.

Homo erectus, the earliest known human ancestor, had roamed around the Indonesian island of Java, where the shell was discovered, at least 1 million years ago. Prior to this discovery, the earliest known engravings date back approximately 100,000 years. Until now, modern humans were believed to be the only species capable of constructing abstract designs.

Experts indicate that if the results are confirmed, the findings, which have been published in the journal Nature, could change perception of the development of human culture.

Stephen Munro, from Australian National University and one of the authors for the report, said in a statement, “With this finding, we might say there are definitely difference between us and Homo erectus. But they might be more like us than we previously thought.”

The discovery came in 2007, when Munro took photos of fossilised freshwater mussel shells that have previously been excavated then stored for over a century. While the engravings weren’t visible to the naked eye, they were clearly captured through digital photography.

According to the Smithsonian National Museum of Natural History, early African Homo erectus fossils are the oldest known early humans to have possessed modern human-like body proportions with relatively elongated legs and shorter arms compared to the size of the torso.