A single-bladed, hand-held, surgical instrument that is used to cut and shape the mastoid process (the large projection of the temporal bone of the skull found immediately behind each ear) during ear/nose/throat (ENT) surgery. It typically comprises a handle proximally which becomes a shaft that terminates in a convex profile with a sharp, semi-lunar, bevelled cutting edge to facilitate tissue removal. It is typically made of high-grade stainless steel as a one-piece instrument and is hand-held by the surgeon who will use a surgical mallet or hammer to manually impart an impacting force to the proximal end of the instrument. This is a reusable device.