This article presents an infrared spectroscopy and X-ray diffraction analysis of residue adhering to a Celtiberian pottery sherd of late Iron Age date from the Arevacian site of Cerro del Castillo, in Ayllón (Segovia, Spain). This residue may be a paste used since antiquity for protective aims. Orange-sepia in colour, made from crushed bones and glue, the paste was used by Greeks and Romans and later in the construction of the cathedrals and monasteries of Europe to confer a warm colour to the stone and to protect it against environmental deterioration. In this article we also suggest a possible ritual use of this paste in the protection of the skin of the Arevaci and Edetani warriors, and the previously unreported pleasant aroma of this material is highlighted. The possible nutritional use of this paste is also considered.