  We examine 172 Ang ultra-high-resolution images of a solar plage region from
the Hi-C 2.1 ("Hi-C") rocket flight of 2018 May 29. Over its five-minute
flight, Hi-C resolves a plethora of small-scale dynamic features that appear
near noise level in concurrent Solar Dynamics Observatory (SDO) Atmospheric
Imaging Assembly (AIA) 171 Ang images. For ten selected events, comparisons
with AIA images at other wavelengths and with the Interface Region Imaging
Spectrograph (IRIS) images indicate that these features are cool (compared to
the corona) ejections. Combining Hi-C 172 Ang, AIA 171 Ang, IRIS 1400 Ang, and
H$\alpha$, 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 front
of some of our cool ejections are likely heated, showing emission in IRIS 1400
Ang. On average, these cool ejections have approximate widths: $3''.2 \pm
2''.1$, (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-C
features might result from eruptions of sub-minifilaments (smaller than the
minifilaments that erupt to produce coronal jets). Comparisons with SDO's
Helioseismic and Magnetic Imager (HMI) magnetograms do not show magnetic
mixed-polarity neutral lines at these events' bases, as would be expected for
true scaled-down versions of solar filaments/minifilaments. But the features'
bases are all close to single-polarity strong-flux-edge locations, suggesting
possible local opposite-polarity flux unresolved by HMI. Or, it may be that our
Hi-C ejections instead operate via the shock-wave mechanism that is suggested
to drive dynamic fibrils and the so-called type I spicules.
