A nicely made ashtray. I don't think it's Czech, at least not Skrdlovice, Chribska or Harrachov, as the rim is wrong. The rim also rules out Afors, from Sweden, which made a similar type of ashtray. I don't think it's sommerso, strictly speaking. There are many glassworks who have made something like this. However, the flat rim combined with the hot-worked lumpy bottom make it quite distinctive so I think you'll be able to id it at some point.
Welcome to the board and, don't worry, you'll soon learn to appreciate johnphillip.
David