DISCOVER CRYSTAL TREASURE - Break open these rocks to reveal amazing crystals inside! Geology doesn?t get more exciting than breaking open rocks and finding crystal treasures. Ag great STEM activity that also makes an excellent gift for girls and boys! COLORFUL VARIETY ? Geodes can form with a wide variety of crystals inside. These geodes have been hand-selected to bring you the best variety available. 100% NATURAL GEODES ? These real specimens may be as big as a tennis ball, or as small as a ping-pong ball. Kids will love the thrill of cracking them open to see the natural beauty inside. This STEM activity emphasizes fun and discovery! 16 PAGE FULL-COLOR LEARNING GUIDE ? You?ll learn all about the fascinating science behind how geodes are formed in the detailed, full-color Learning Guide. National Geographic educational toys make science and learning fun, and are the perfect STEM gifts for boys and girls! HIGH-QUALITY EDUCATIONAL TOYS - We're proud to make the highest quality hands-on science toys, and all our products are backed by exceptional service. If your experience is less than stellar, let us know and we'll make things right!