What the heck is a pumice stone and why does it work such wonders on our feet? Pumice stones form when lava and water mix together. When the lava cools rapidly, it results in a porous, foamy-looking texture that can help remove dry and dead skin. This isn’t a modern discovery—the pumice stone has been a known exfoliation tool going back as far back as 100 B.C. Our ancient ancestors discovered that the stone, while light, was abrasive enough to lift dead skin and smooth out texture on areas such as the feet, knees and elbows. Here’s what you need to know so your feet are prepped and you get the most out of the experience.