Wash watermelon under cool running water and pat dry.On cutting board, place watermelon on its side and cut off 4 inches from one end of watermelon to provide a sturdy base.
Cut remaining watermelon in half lengthwise.Hollow out both halves of the watermelon with spoon or scoop, reserving watermelon pieces to dice up for serving or cutting out mermaid shapes.Use dry erase marker to trace mermaid tail freehand lengthwise across one entire half. With knife of your choice, carefully trim away to form the outline of mermaid tail. Use the channel knife to form scales and details.For added detail, brush on edible turquoise shimmer powder/disco dust (purchased at cake decorating store or craft store).Use pencil-sized dowels to secure the mermaid tail to top of base. Decorate with watermelon cubes or mermaid watermelon cutouts and serve.
Layer watermelon, yogurt and granola into molds and top with yogurt and watermelon chunks.Freeze push pop molds and enjoy.