With the 172 building pieces in this kit, you can assemble a real robot that looks like a cute hedgehog. This unique pet has a built-in sound sensor and is programmed to react to your claps. Clap once, and your hedgehog curls up into a ball and rolls over one time. Clap multiple times, and it will roll again and again, tumbling once for each clap! Watch how different patterns of claps instruct your hedgehog to do different tricks--make it bristle its spines, scurry around, spin, and more!