Walnut, specifically crushed walnut shells or powder, is a natural exfoliant often used in skincare products for its abrasive texture. It can be found in various forms like ground walnut shells or finely milled walnut powder, depending on the desired level of exfoliation. Walnut shell powder is commonly used in physical exfoliants like face and body scrubs to help remove dead skin cells to create a smoother, more polished skin texture. But, because of concerns about its potential to cause skin irritation and damage, many skincare experts and brands have shifted to promote healthier, less abrasive exfoliation methods like chemical exfoliants and non-abrasive physical exfoliants.