Magic Water Book

It sounds like you're describing a type of children's activity book or art set, often called a "Magic Water Book" or "Magic Water Coloring Book." These books come with special pages that reveal colors or images when they are "colored" with water, usually applied using a magic water pen. Here's how these books typically work:

1. Magic Water Pen: This is a pen-like tool that is filled with water. The pen has a brush tip, and when you apply water to the pages of the book, the colors or images gradually appear.

2. Reusable: Since the book works with water, once the page dries, you can color it again, making it reusable. The colors or images fade away after drying, allowing for multiple uses.

3. Doodle and Creativity: Many of these books feature themes like animals, landscapes, or abstract patterns, and they encourage creativity while being mess-free. They are popular for young children as they can safely create artwork without the mess of traditional paints or markers.

4. Learning & Fun: These books can also help kids learn about colors, shapes, or even numbers and letters while having fun with the interactive pages.