A keyhole millstone is a type of millstone used in traditional grain milling, characterized by its keyhole-shaped central hole. This design enhances the milling process by allowing for easier alignment and stability during operation.

The keyhole feature may have practical engineering benefits, such as improving the distribution of forces during milling or facilitating the attachment of the stone to a driving mechanism. Keyhole millstones often reflect historical milling techniques and can be found in some traditional or heritage milling contexts.

This substantial piece would grace any garden as a sculptural element or artisans may incorporate them into sculptures or other artistic endeavors.