Three-hundred feet inside Gorham’s cave just east of the Strait of Gibraltar, a team of European researchers uncovered strange markings on a bedrock ledge that jutted out from the wall a few feet above the cave floor. The really strange part: The markings were very similar to our modern-day hashtag. But that’s just “scratching the surface.” On this episode, we do some digging into the mystery of the Neanderthal hashtag found carved in a cave near the Strait of Gibraltar.