Se han estudiado tres pulidores de piedra pómez con ranuras de características formales y huellas de uso muy similares. Dos han sido hallados en el nivel III del yacimiento de la cueva de Santa Catalina (Lekeitio, Bizkaia); este nivel ha proporcionado un abundante y variado conjunto tecnoindustrial del Magdaleniense superior, datado en el Tardiglaciar. El tercero procede de un nivel Magdaleniense de la cueva de Aitzbitarte IV (Errenteria, Gipuzkoa). La función de estos objetos está relacionada con los procesos de fabricación de agujas o apuntados en hueso, asta u otras materias como la madera. Pulidores semejantes del mismo período cultural, también en piedra pómez, se han localizado en un territorio relativamente limitado, en el suroeste de Francia, junto a la Cordillera pirenaica. El área de localización de todos estos útiles era cercana a la costa, ecosistema en el que sería recogida la piedra pómez arrastrada por las corrientes marinas hasta el litoral del Golfo de Bizkaia, del que se difundiría hacia zonas interiores. ____________________________________________ ABSTRACT Three fragments of pumice stone have been recovered at two sites near the southern coast of the Bay of Biscay, with extensive grooves and traces of wear caused by their use as polishers. Two come from level III of the Santa Catalina cave, dating from between 12900 and 15000 Cal BP, and one from level IV of Aitzbitarte IV, with no radiocarbon dating. All three were found in Magdalenian cultural contexts. The most plausible hypothesis concerning their acquisition is that they were picked up on the beaches near the settlements. The Santa Catalina cave, now open on a cliff, was about 5 km from the coast at that time. The archaeological record from level III of Santa Catalina attests to the fact that its occupants fished extensively and collected marine resources during the final phases of the Late Glacial. The Aitzbitarte IV cave was not far from the sea either. A small number of similar tools were found on the northern slope of the Pyrenees, which have also been attributed to the same cultural period. With the exception of one found in a cave in the central Pyrenees, they all lie in a small area of south-western France, in settlements close to each other. These pumice stones must have had a similar origin to the specimens found in the cavities along the Cantabrian coast: volcanic areas in the Arctic or the Caribbean, from where they would have floated, carried by the sea currents. It is very possible that it was obtained by being collected on the Atlantic paleo-coast, although it cannot be ruled out that, in some cases, it was due to exchanges between neighbouring communities. These types of tools have been linked to working with hard animal materials, in particular with making needles or other pointed objects, although we should not rule out other possible uses.