A Chinese friend brought me some to try. The white outer part is made of glutinous rice but the inside is stuffed with various fillings -- peanut paste, sweet potato paste, even chocolate. This batch went into boiling water in my new cooking pot. These are actually made with tapioca paste so that as they heat up, the white outer case becomes transparent and you can see the color of the filling inside. They looked like big fish eggs.
I wrote a ribald insinuating headline for this post but decided that no-one wants to hear that kind of joke from a woman my age. But if you do, follow this link.