The crisscrossed pattern, drawn on stone 73,000 years ago, wasn’t used as shorthand for #artlovers, but the hashtag-like design may very well have had symbolic intent. The sketch by early humans, unearthed at an archeological dig site in a South African cave, was drawn with a red ochre crayon—and it may be the earliest drawing ever discovered.

Although the crosshatch design is simple, Christopher Henshilwood of the University of Bergen in Norway suspects it was meaningful, especially considering that similar markings have appeared on artifacts from different Stone Age eras and locales. In a study published today in Nature, Henshilwood and colleagues describe the unique characteristics of the newly analyzed artifact. The pattern may be similar to other ancient markings, but its creator made use of a new technique for the era: color drawing.

“They took a piece of ochre, knocked a flake off it to sharpen it and used it as a pencil or crayon on a very smooth surface that was previously a grindstone,” Henshilwood says. The design’s lines end abruptly on the edges of the silcrete stone, suggesting the piece was removed from a larger grindstone and that the original drawing was bigger. Just how big is an open question that might be answered if the rest of the grindstone is found somewhere in the area.