Design a single, rusted key with a unique and striking appearance. The key should have an intricate, ancient design with ornate carvings and a large, worn-out head. Its metal surface should show heavy corrosion, but there should be a faint, eerie glow highlighting the edges, making it stand out in dark areas. The key should look like it has immense significance, almost like a relic from a forgotten era, placed in a hidden or secretive location to attract attention