Cheese crystals are whitish, semi-solid to solid, slightly crunchy to gritty crystalline spots, granules, and aggregates that can form on the surface and inside of cheese. Cheese crystals are characteristic of many long-aged hard cheeses. Hard cheeses where cheese crystals are common and valued include comté, aged cheddar, grana cheeses like parmesan, grana padano, and Pecorino Romano, as well as old gouda. However, in some cheeses, like industrial cheddar, they are considered a production defect.