A Rolling Glass Sphere

I dropped down from the windowsill to the hardwood floor with a soft, bouncy thud. Sitting right near the low glass coffee table was a clear, heavy glass marble resting in a shallow rug groove. I paused, cocked my snout, and delivered a gentle, calculated nudge against its glossy curve. It gave way immediately, gliding smoothly across the floorboards with a tiny humming sound. I trotted closely behind, watching it reflect the room upside down until it bumped softly into a wooden table leg and wobbled to a halt.