Left panel: observed sunspot imaged in G-continuum. The gray-scale has been chosen to better show umbral features. The direction toward disk center is indicated by the arrow labeled “DC” at the upper right corner; right panel: simultaneous and cospatial Ca ii H line core image of the same sunspot. The gray-scale is chosen to enhance fine structures in the umbral chromosphere. Circles show the locations of all jet-like events identified in the time series. Circles filled in different colors mark the locations of events discussed in the main text. White boxes show the fields-of-view of events discussed in the text and shown in Figs. 2–4 (from left to right). The temporal evolution is shown in a movie available in the on-line edition. The movie uses a slightly different gray-scale to highlight the features.