Our silk pillows use silk floss filling in the form of stacked thin sheets of tangled silk threads. The nature of the filling and the unusually strong silk fibers in the silk floss means that: It is unlikely that the filling inside the pillow shell will move around and clump together to give the pillow an uneven shape. It is difficult for the silk threads in the filling to succumb to pressure and deform, allowing the pillow to regain its original form once the force is removed.Of course, silk fibers are not immune to deformation and will eventually the change in the pillow’s shape will become profound enough for you to notice, but this process is prolonged and can take 5-10 years.