http://news.discovery.com/space/curiosity-finds-a-floating-spoon-on-mars-150901.htm
OK, I get it, it's not really a spoon but its fine, thin fragile looking structure just amazes me.
Yes, it's an interesting formation, and I think there's a thread about it here somewhere, as this is from last year. :)
Yes, there is a past discussion on this, and I did look for it, but haven't found it yet!