Also called shell-stacking. This is an extremely primitive kiln-filling method that predates bud stacking. When firing vessels one on top of another, shells are placed between the vessels to prevent them from welding together, to improve the seating of the vessels, and to prevent distortion of the product.
This method is used in the Karatsu, Takata, and Takatori kilns. The Takada kiln uses hishi shells because they are the most fire-resistant, but they can only be used once.
Shell-shaped plateau
A piece with shell marks on the underside of the base. Found in Korean ceramics. It is used in place of sand.