Interesting Christmas calendar: 24 kinds of rock, gem and mineral specimens, 24 openings (which may contain the same stone or stones not shown in the figure), have different surprises every day to form a lasting attraction to children. The ultimate specifications collection: perfect independent collection or added to any children's specimen collection, including 24 raw stones and polished ore samples. A great gift for boys and girls. Time concept: geology is more exciting than breaking rocks and looking for crystal treasures; Calendar is also a good way to teach children the art of numbers, time and patience. Parents can also give their children extra surprises on the specified date. Perfect gift: children and adults like this gift. Note: not edible. Please do not put it in your mouth. It is not suitable for children under 3 years old. Material: stone size: about 21 * 16.4 * 5cm / 8.27 * 6.46 * 1.97in