There's some beauties! I'd invite you to go all Macro on some of these guys, too. I've always thought these were very cool, but never dug a lick of even one of em, alas.
The sulphide marbles I have pictured are all German. They are single-gather marbles with one pontil. They were produced from the mid 1800's to around 1910. The most common have roosters, lions and other animals. You can find numbers, humans, and all sorts of odd things. The rarest and most expensive examples have painted figures or colored base glass. Sulphide marbles are worth anywhere from $60-$5000, with the bulk of them being worth $60-$100.
Marble collectors typically frown on polished marbles, but sulphide's don't loose as much value as other types due to the fact that they do not loose any design in the process.
The glass magnifies the figure in the center. I have seen them busted open and its amazing how small the figures actually are!