That centre rod slides out until the ferrule is at the cap - giving quite a long support visible above the glass. So it is very unlikely to be a lustre.
Logic for my suggestion.
At first I thought that it might be one of the many 'lightbulb' sculptures but the cap is not airtight and the lump is not the closing of an evacuation hole, plus the rod slides out so then I thought:
The nose gives it a dolphin like appearance and with the construction of the metal parts, the irregularity of the flashing all say to me a piece of Art. In the 70s/80s lots of largish glass collages were made and I doubt all got sold and must have been broken up at some point. I could easily imagine a hanging construction with the objects having different lengths of support to set the height of each piece