  Recent observations by the Interface Region Imaging Spectrograph (IRIS) have
revealed pockets of hot gas ($\sim$2--8$\times$10$^{4}$ K) potentially
resulting from magnetic reconnection in the partially ionized lower solar
atmosphere (IRIS bombs; IBs). Using joint observations between IRIS and the
Chinese New Vacuum Solar Telescope, we have identified ten IBs. We find that
three are unambiguously and three others are possibly connected to Ellerman
bombs (EBs), which show intense brightening of the extended H$_{\alpha}$ wings
without leaving an obvious signature in the H$_{\alpha}$ core. These bombs
generally reveal the following distinct properties: (1) The
O~{\sc{iv}}~1401.156\AA{} and 1399.774\AA{} lines are absent or very weak; (2)
The Mn~{\sc{i}}~2795.640\AA{} line manifests as an absorption feature
superimposed on the greatly enhanced Mg~{\sc{ii}}~k line wing; (3) The
Mg~{\sc{ii}}~k and h lines show intense brightening in the wings and no
dramatic enhancement in the cores; (4) Chromospheric absorption lines such as
Ni~{\sc{ii}}~1393.330\AA{} and 1335.203\AA{} are very strong; (5) The 1700\AA{}
images obtained with the Atmospheric Imaging Assembly on board the Solar
Dynamics Observatory reveal intense and compact brightenings. These properties
support the formation of these bombs in the photosphere, demonstrating that EBs
can be heated much more efficiently than previously thought. We also
demonstrate that the Mg~{\sc{ii}}~k and h lines can be used to investigate EBs
similarly to H$_{\alpha}$, which opens a promising new window for EB studies.
The remaining four IBs obviously have no connection to EBs and they do not have
the properties mentioned above, suggesting a higher formation layer possibly in
the chromosphere.
