Looks like one of those foreign marbles referred to as pincers (or pinchers, don't recall). Anyhow, machine made probably 50-70 years ago judging by the lots I've found them in previously
Hangathered for sure, but unless the pontil is ground/faceted and the marble is a lot more "round" than it looks in the pics I'd say No to Greiner for the OP
Based on how out of round it appears in the pics....I'd guess it was originally intended for something other than a marble. Jewelry or lamp finial or something
Yes, I agree with earlier opinions on subject marble. Pretty beat, but good place holder for collectors on a budget, if they are in the market for this type