Answer:
Children keep their assets in this.
One time every year, there is a very special day. Little have the same, everyone party a different way.
Fred and Wilma's child, named after a stone.
A locked sphere without hinges or key. Break me open and golden treasures you'll see
These women make princesses scrub floors and sometimes try to poison them with apples.
I appear in the morning. But am always there. You can never see me. Though I am everywhere. By night I am gone, though I sometimes never was. Nothing can defeat me. But I am easily gone.