Wee Globular Bottle, Ring Pontil, In-Rolled Lip; What've I Got, Here?

~3 3/4" high, ~2 3/8" max diameter, ~1" lip OD; weight is 55 grams.

Pic 3 vaguely shows the rolled-in lip, and also the crud that is pretty heavily & uniformly covering the entire inner surface...I haven't attempted cleanup, so cannot say whether that deposit is hard or soft. The glass has a single bubble, pic 6; the neck, just under the flared lip, has a wrinkle, pic 4, an' what looks like a tool-mark, pic 5.
The flask is well shaped & proportioned, quite uniformly globular, with a modest kick-up, the ring pontil nearly centered. The glass color is a rich, dark molasses-amber; the exterior surface is matte, but whether that is as-made or the result of since-made age-related externals (like the interior) is beyond my meager skills to declare.

Your comments are treasured, especially concerning approximate age or possible place of origin. As always, thanks for lookin'!

 

missing a stopper, likely !

 

Black glass pontil flask.With the inner lip materialization it could be a 'digger' that might have been tumbled (to scour/clean) and then possibly oiled.
I'd consult a good bottle forum for clues to it's age-there's a number of genuine & repros.