He wouldn’t have noticed it if he weren’t a dentist. Being one, he spotted it right away — and wrote about it to The Washington Post. Our floor and wall tiles often come from materials that may have formed millions of years ago. A mirror-polish granite tile has many random features — we neither can make sense of them, or we do care to see what they are.

But a man, whose Reddit username is Kidipadeli75, said he was visiting his parents’ home in Europe when he spotted something odd in a floor tile. The travertine tile came from Denizli Basin of western Turkey. Travertine is a type of limestone that forms through the precipitation of minerals from mineral-rich water, typically in hot springs or limestone caves. It is a sedimentary rock composed primarily of calcium carbonate (CaCO3). The Denizli Basin was formed between 0.7 million and 1.8 million years ago. The feature that caught Kidipadeli75’s eye was a horseshoe shaped white material with some squarish shapes embedded in it. That was where Kidipadeli75’s expertise as a dentist came in handy. He instantly recognised it to be a mandible — lower jaw — of a man. The square shapes were remnants of his teeth.

The owner of the mandible and the teeth should have died at least 7,00,000 years ago. The lower jaw and teeth became part of rock. If the rock had not been sliced into tiles for homes, they would have probably been extracted and studied. But it was outlandish to file a dead man’s teeth in a floor tile of a home, thought Kidipadeli75. So, he wrote to WaPo.