Boys like rocks. They collect them. I find rocks in their pockets. I find them under the sofa and in the bathtub. I find rocks at the bottom of the hamper and I find them in my dryer. Thinking I might be able to contain the rock collection to a single spot, I gave my boys a nice mason jar to keep their special rocks in.
Boys also like to shake things. Especially if the shaking creates noise. Noise that is made by their special rocks klinkety-klanking around in their glass mason jar.
Just fyi, it doesn’t take a whole lotta klinkety-klank before a mason jar shatters.