This was a huge disappointment to my kids - 8, 10, 12. There were no crystals inside any of them! They were extremely hard to break, but we decided that geodes that scientists discover probably are also hard to break. Once we got them open, they were sorely disappointed - not a one had any crystals. The only good point I have for this product is that I taught the kids that scientists don't always find "cool" stuff as they are on their digs....