Ever wondered what is in those leg weights?

For those of you who are curious, we discovered they are filled with hundreds, no thousands, actually probably millions of teeny tiny metal balls. Metal balls that really hurt your feet when you step on them. They rank right up there with legos and Barbie shoes. How did we discover this? Sunday (the day of rest, and apparently that means experimentation when you are a young boy and your parents are trying to rest), we heard this noise that sounded like frying (as in oil) gone wrong - there wasn't any associated smell but we knew we had to investigate. The boys (we don't know exactly which one - I can't wait for those family talks when the children have moved out of the house because then I will be able to get true confessions out of them) discovered that one of my leg weights had a small tear in it and being boys, they just had to make it bigger and then create a waterfall effect with the contents over the side of the 2nd floor railing down to the wood floor below. Hence the deafening noise that sounded like frying. They were required to clean the mess to the best of their ability, but it is now Wednesday, and after sweeping and vacuuming each day, I am still finding teeny, tiny little metal balls all over. I think I will be finding them for months. Keep in mind, these are the boys that dumped 5 pounds of sugar on the living room carpet to recreate Thomas being stuck in the snow. At least it was granulated and not powdered.