Final answer:
Microdermabrasion is a form of mechanical exfoliator that involves shooting aluminum oxide crystals at the skin.
Step-by-step explanation:
The form of mechanical exfoliator that involves shooting aluminum oxide crystals at the skin is known as microdermabrasion. In microdermabrasion, a device sprays tiny aluminum oxide crystals onto the skin and then vacuums away the dead skin cells and crystals. This process helps to exfoliate the skin and improve its appearance.