probably most folk already know this one, but the first I've found in a charity shop, so not expensive. Am sure I've seen smaller copies (this one is the largest size at 6.25 inches tall) - might the copies be from China or eastern Europe?
Apparently designed way back in 1936 by Alvar Aalto, and produced on and off in the intervening years in a variety of colours such as red, olive, clear, opal, blue and 'gray' which is what I think this colour is supposed to be (though not sure), but think in the U.K. we might say midnight or smoky. Gray is apparently one of the most recent colours - c. 2000.
Worth big bucks it seems if you have a green or red example.
Officially described as ...... 'biomorphic form with free-flowing and undulating walls, and they were certainly being made as recently as 2002, and for all I know may still be in production. this one is acid backstamped with... ALVAR AALTO, and still has the factory label.