by @russ10.

After this general description, we analyze in the next sections the shell G353.12+0.86, the  region G353.2+0.9, and the large shell.

The shell-like feature G353.12+0.86
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The central region of NGC6357
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Two optical shells are apparent near the centre of Fig. 1. They are centred at 172435, and at 172513, , respectively. The central cavities and surrounding envelopes are clearly identifiable in the composite images displayed in Figs. 1, 2, 5, and 7. Figures 1 and 7 reveal that the intense  emission that delineates the shells is almost completely encircled by emission at 8 $\mu$m. A comparison of Figs. 1 and 5 shows that both optical shells have radio counterparts.

The optical shells are separated by a dust cloud clearly discernible in Fig. 1 These images suggest that this dust cloud is a foreground object. In this scenario, both shells would be a unique structure with the most massive stars inside.

The CO emission distribution shown in Fig. 8 reveals a region without molecular emission centred at 172445,$-$3416, coincident with the position of the two optical cavities. As pointed out before, the CO hole is almost completely encircled by molecular gas with velocities in the range \[–7.5,0.0\]  (indicated 