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We examine 172 Ang ultra-high-resolution images of a solar plage region fromthe Hi-C 2.1 ("Hi-C") rocket flight of 2018 May 29. Over its five-minuteflight, Hi-C resolves a plethora of small-scale dynamic features that appearnear noise level in concurrent Solar Dynamics Observatory (SDO) AtmosphericImaging Assembly (AIA) 171 Ang images. For ten selected events, comparisonswith AIA images at other wavelengths and with the Interface Region ImagingSpectrograph (IRIS) images indicate that these features are cool (compared tothe corona) ejections. Combining Hi-C 172 Ang, AIA 171 Ang, IRIS 1400 Ang, andH$\alpha$, we see that these ten cool ejections are similar to the H$\alpha$"dynamic fibrils" and Ca ii "anemone jets" found in earlier studies. The frontof some of our cool ejections are likely heated, showing emission in IRIS 1400Ang. On average, these cool ejections have approximate widths: $3''.2 \pm2''.1$, (projected) maximum heights and velocities: $4''.3 \pm 2''.5$ and $23\pm 6$ km/s, and lifetimes: $6.5 \pm 2.4$ min. We consider whether these Hi-Cfeatures might result from eruptions of sub-minifilaments (smaller than theminifilaments that erupt to produce coronal jets). Comparisons with SDO'sHelioseismic and Magnetic Imager (HMI) magnetograms do not show magneticmixed-polarity neutral lines at these events' bases, as would be expected fortrue scaled-down versions of solar filaments/minifilaments. But the features'bases are all close to single-polarity strong-flux-edge locations, suggestingpossible local opposite-polarity flux unresolved by HMI. Or, it may be that ourHi-C ejections instead operate via the shock-wave mechanism that is suggestedto drive dynamic fibrils and the so-called type I spicules.

Hi-C 2.1 Observations of Small-Scale Miniature-Filament-Eruption-Like Cool Ejections in Active Region Plage