Growth dynamics of pyramid-shaped features that emerge during etching of silicon(100) surfaces in 2 M aqueous potassium hydroxide solutions have been investigated using in-situ atomic force microscopy. Micropyramids were found to grow continuously from a scale-shaped structure that is present on the surface during etching. In addition, two characteristic removal mechanisms of fully developed pyramids could be identified. It is suggested that these etching mechanisms are unique to pyramids and not comparable to the etching properties of single crystal surfaces.