Grullo or grulla is a color of horses in the dun family, characterized by tan-gray or mouse-colored hairs on the body, often with shoulder and dorsal stripes and black barring on the lower legs. In this coloration, each individual hair is mouse-colored, unlike a roan, which is composed of a mixture of dark and light hairs. The several shades of grullo are informally referred to with a variety of terms, including black dun, blue dun, slate grullo, silver grullo, silver dun, or lobo dun. In the Icelandic horse, the grullo color is called gray dun, in the Highland pony it is called mouse dun, and in the Norwegian Fjord horse, grå or gråblakk (literally, "gray dun").