When the original Neanderthal skull with the heavy brow and thick bones was found by quarrymen in Germany’s Neander Valley in 1856, British geologist William King interpreted them along the lines of phrenology and scientific racism. He determined that the skull must have come from an inferior species, reports Jon Mooallem at The New York Times Magazine. Writing about the skull, King mused that “The thoughts and desires which once dwelt within it never soared beyond those of a brute.”

That stereotype stuck for well over a century and still persists in popular culture today. But recent research shows that Neanderthals weren’t the stoop-shouldered grunting cavemen found in Gary Larson's "The Far Side" comic strip. They were similar to humans of the day, capable of making fire, speech, burying their dead and even engaging in symbolic behavior. And the latest piece of evidence found in a cave in Krapina, Croatia may suggest they had another trait in common: they liked to pick up cool rocks.

According to a press release, a group of international researchers re-examining material excavated from the cave, where archaeologists found 900 Neanderthal bones between 1899 and 1905, came across an unusual split limestone rock. It stood out from the other 1,000 pieces of stone collected because of its composition and the interesting black lines spidering across its face.

“It looked like it is important,” David Frayer, professor emeritus of anthropology at the University of Kansas who is co-author of a study of the rock appearing in the journal Comptes Rendus Palevol. “We went back through all the collected items to make sure there weren't other rocks like it. It just sat there for 100 years like most of the other stuff from the site. The original archaeologists had described stone tools, but didn't pay any attention to this one.”

According to Ruth Schuster at Haaretz the researchers believe that the Neanderthals brought the rock to their home cave simply because they thought it was interesting. In other words, whoever picked it up was rock collecting. “The fact that it wasn’t modified, to us, it meant that it was brought there for a purpose other than being used as a tool.”

If that is the case, it is just one more piece of evidence that Neanderthals were much more sophisticated and similar to early modern humans than previously thought. In another paper in 2015, Frayer describes discovering a group of claws from the white-tailed eagle also found in the Krapina material with cut marks indicating they were worn as jewelry. Other researchers have found lumps of red ochre at Neanderthal sites, indicating that they may have used the pigment for ceremonial purposes and possibly to produce art. There’s also strong evidence from a Neanderthal burial in France that they ritualistically buried their dead.

“I think there’s been a trickle of evidence for a while now and there’s mounting evidence for Neanderthals engaging in symbolic behavior in sites in Spain, Croatia, and France,” Briana Pobiner, a research scientist with the Smithsonian’s Human Origins Program tells Smithsonian.com. “It goes a long way toward changing the idea of Neanderthal’s being brutish and inferior.”

In fact, Mooallem reports that the more we learn about Neanderthals, the more they resemble the anatomically modern humans that they eventually shared the world and even interbred with. They hunted game, wore feathers, were capable of speech, buried their dead and made some sophisticated products, like glue from birch bark.

“The real surprise of these discoveries may not be the competence of Neanderthals but how obnoxiously low our expectations for them have been— the bias with which too many scientists approached that other Us,” writes Mooallem. “One archaeologist called these researchers ‘modern human supremacists.’”

According to the press release, the rock found at Krapina likely came from outcrops of biopelmicritic grey limestone found just a couple miles north of the cave. Either a Neanderthal found it and transported from the outcropping or it was transported closer to the cave by a nearby stream and then taken to the cave by a curious hominid.

Pobinar doesn't dispute that the rock may have been transported to the cave by a Neanderthal, but she doesn't think the find is quite as important as some of the other recent evidence. “The rock doesn’t blow me away when we’re thinking about symbolic behavior in Neanderthals,” she says. “It’s interesting and pretty, but it doesn’t tell help us peer into the minds of the Neanderthals. It’s not as compelling as some of the evidence from the same cave, like the talons from the white-tailed eagles.”

Frayer admits that the rock is just a minor piece of evidence in putting together the Neanderthal puzzle, but it does add another pebble of insight to our evolutionary neighbors.