Grinder was one of the four great D'ni digging machines. Its age is undocumented, unlike its three older siblings, but it was present at the opening of the Tijali Mines, 1800 years prior to the excavation of the Shaft. Grinder is not only the youngest, but also the largest and loudest of the four diggers, built especially for the opening of new mines. Together with Old Stone Tooth, it drilled straight up toward the surface, digging out the bulk of the Great Shaft.