My quick and dirty assembly of the images here - 1 Meg jpg - needs rotation and a bit more care. But for now....
Crude assemblyWell,
If Opportunity goes in there, it ain't ever coming back out!
Oh for a space suit and a rock hammer...
Thinking aloud: There may be some spectacular scale cross-bedding in the upper layers, which *could* be interpreted as fossil craters, healed over by more layering. hard to say - need to think about this in 3D!
On Earth, the knobby bulges in the wall would be fossil reefs. Not sure what they are here.
I guess we'll do a lot of circling and sniffing to see what can be seen all around the rim, while sizing-up that potential death-slide into the pit.
Oh, and the features inside the crater *are* dunes, not exposed bedrock.