It's not a rock
The feature I'm talking about in PIA04995 is not a rock, but a rather large, generally elliptical, light colored, possibly reflective feature, near the horizon in PIA04995.
It looks like a depression, or possibly crater, which has filled in with something that doesn't look to me like it would be dust - due to the rather crisply defined margins. The area in question is approx 350x30 pixels in PIA04995.
Spaking of rocks in PIA04995, I see a few that are rather smooth and shiny.
S
