True, although they seem to think it is a hole of some kind, because of the light not being visible that enters it:
Yeah... I'm not trained to analyze pictures like these people at NASA... but in a few of them there is either:
a) A lighter colored material exactly opposite of the shadows which coordinates perfectly with the angles of the other protruding objects in the picture...
- or - b) There is something actually sticking up near the hole on the side exactly opposite of the shadows which coordinates perfectly with the angles of the other protruding objects in the picture...
Now, if an underground chamber of some sort was going to have part of its roof cave in, it would be sort of weird for it to leave lighter material near only one side of the hole, and it would also be very weird for it to leave material above the hole itself around one half of it...
I would really like to see these from another angle, I have a feeling that they are just misinterpreting these.
However, I have no way to explain (F or the two largest photos) because they don't seem to have that lighter semi-circle around them like the others...