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Hi.
The shape is very much like the low domed Arculus weights, and the bubbles all over suggest Arculus too! So I am fairly sure it is an Arculus / Walsh Walsh item (Walsh Walsh took over the Arculus factory in 1930, and kept on making the same kind of things). It probably started life as a paperweight, but another possibility is that it is a very cut down base of a bottle - they tend to turn up fairly regularly.
Alan