A rather long Victorian glass dump?
For info (and fun, with apologies to all readers) on what can become a complex discussion ...
The item is not a "dump" (aka "dumpy") in the sense of a "door-stop" which was the terminology in earlier books, and stated in Harold Newman's "An Illustrated Dictionary of Glass", published 1977.
In some collector circles, especially paperweight collectors, this item would be referred to as a "whimsy" or a "paperweight related item". It gets classified as such because it is made from green bottle glass just like the door-stops ("Dumps"). But because it does not have the required stability to stand alone and hold open a door, it cannot be a "Dump" / door-stop. But wait ...
... A "Dump" was apparently named as such because it used so-called "end of day" glass in preference to simply dumping it out of the furnace. On that basis, anything that was likely 19th or early 20th century and made at the "end of the day" from bottle glass could be called a "dumpy item". And yet ...
... There is another complication. The true door-stops were indeed of a size, shape and weight that would suit the function of holding open a door. Many were decorated internally with tinfoil petaled leaves, or lots of air bubbles, or had sulphide inclusions and so on. So what about items that looked just the same but were a tad too small or a bit too thin or just plain wobbly? They do exist, so what were they if not "Dumps"? ... They were (in the more modern language of collectors) "paperweights" or "mantel ornaments" or "whimsies".
And that is what the OPs item is - a whimsy. Unless of course, it was purposely made, either on contract or in large numbers, for a specific role and not just something put together at "the end of the day". ...
... In which case, Christine's "industrial" idea would seem very reasonable - and maybe it was just what it looks like, an industrial pestle (or a very solid "drum stick" ... or maybe even a truncheon).
Sorry about all that ... and all the dots ...