The Goose Layed Frozen Eggs

When it gets cold enough, me and my brothers fill up water balloons (both small and large) and let them stay outside over night, what usually happens is that the outside will freeze, but inside there will be water, so we make a hole and let the water come out and we have a hollow bowl. This was a small water ballon that ended up looking like an egg, you can't tell, but there is water trapped in the egg. In other words, it is just something fun to do before the snow comes, lol.