During what should have been a routine home renovation, a simple discovery stopped a group of homeowners in their tracks — and ended up sparking an online frenzy. Hidden inside an old doorframe was a strange six-inch-long mechanism made of metal, with a small stone affixed to its end. Though it looked mundane at first glance, its purpose wasn’t obvious — and the mystery surrounding it quickly captured people’s imaginations. The Discovery It started when a couple began restoring their early 20th-century home. While replacing interior doors, they found the odd object lodged deep inside the wood — as though…