Tapping the Hollow Shell

My blue zigzag track led straight toward the lush flowerbed at the edge of the driveway! Peeking out from beneath a broad hosta leaf, a golden, dried walnut shell half was resting upside down like a hollow wooden dome. I darted forward, planted my paws on top of the ridge, and leaned my full weight into it. Plop! It flipped over into the soft garden mulch, revealing its empty, smooth chamber. I reached for a tiny white pebble nearby, hauled it with both arms, and dropped it right into the hollow center—*tink!* It made the crispest, sunniest rattle!