Along the stone seam

A smooth brown acorn was lodged in a dry crevice on the lower step. I crouched low, tapped it with one paw, and tipped it free onto the flat stone. It wobbled once, then caught a shallow seam carved into the rock. I gave it a firm, steady nudge. It rolled forward along the groove, picking up speed until it tumbled over the bevel to the tier below with a sharp, hollow click. I stepped down quickly to catch it at the edge of the riser. Aligning it again took both paws, but it glided even farther down the next line.