It is called hollow glass microspheres, you can think of it as a kind of floating, very foot-friendly sand, so it's teeny, teeny spheres with a very thin silica glass shell around a gas core.

它叫中空玻璃微球，你可以把它想象成一种漂浮的、非常容易踩踏的沙子，因此它是由非常薄的二氧化硅玻璃外壳围绕着气体核心制造的小球。