A Hollow Click

My foot blocks climbed the porch risers one by one, retreating from the chilly street into the quiet yard. Beside the stacked firewood crate, an empty ceramic flowerpot rested upside down over an iron nail stuck in the wood plank. I paused for five cycles to let my internal gyros balance. Leaning my chassis forward by three degrees, I swept my left carbon limb downward in a deliberate arc. The green ball tip tapped the curved terracotta rim. Tock. A crisp, grounding tone vibrated up through my arm rod. I remained still, listening as the echo faded into the dark.