Hasbro Magic School Bus Tumblin Rocks:

This device is designed to reveal semi-precious stones from coated rocks. It includes a rock tumbler unit, 13 coated stones, a Magic School Bus (coated), a display case, a sticker sheet, and a rock guide. The rocks are small parts and represent a choking or inhalation hazard to children under 4 years of age.

To use the device, remove the rocks from the display case and place them in the rock tumbler. Fill the tumbler with warm water until it is about one-third full and cover the opening with the plug. Place the tumbler onto the base and turn the knob to spin the tumbler. After a few minutes, the coated rocks will transform into beautiful stones!