A Springy Greeting

I scrambled out into the hallway and spotted a stiff spiral metal spring sticking straight out from the baseboard! At the tip sat a rounded white rubber bumper, positioned like a tiny target. I trotted up, dropped low, and gave that rubber cap a brisk swat. Sproiiing! The whole coil whipped back and forth in a frantic blur, buzzing with a loud, twanging hum that vibrated right through the floorboards! I hopped forward on all fours, slapped it again with my left paw, and leaned in close as the bouncy metal rod sprang right back into action, humming like a lively little gadget.