The origin and affinity of the problematic Nuia Maslov is reappraised from exceptionally preserved specimens in Upper Cambrian (Sunwaptan) rocks of the Llano Uplift, central Texas. Nuia is suggested to be a radial calcitic ooid that has nucleated on fragments of reworked filamentous calcimicrobes rather than a separate microorganism as has been assumed previously. Nuia is found predominantly in intrareef grainstone accumulations, as well as in interreef grainstones, invariably accompanied by other bioclastic debris showing similar radial calcite ooid overgrowths.