Interesting. So #1 was too easy, and #2 proved too ambiguous and difficult. I agree that "grains of some powdery stuff" was about as close as anyone could reasonably get to the answer. Hopefully #3 will strike some balance between too trivial and too impossible.
Can you identify what this is?
It was pretty clear to our contestants that this was the bottom of a glass bottle. I am in Spain, however, so I'm surprised that no one correctly guessed that it was a wine bottle.
by erikrasmussen, on Flickr")
Ridges on the bottom of a wine bottle.