I have here a piece of glass that I have seen around my house for a while but no one in my family has any idea what it is. It was acquired from an auction many many years ago with some bottles in a box. It looks somewhat like an insulator so i decided to try my luck :-)

It has an aqua blue colouring.

the bottom right photo is what I'm guessing is the bottom because it bubbles out then has a bit of a lip rounding upwards, also it has a piece sticking out like it could hold a wire under it. It's all glass

thanks in advance for any help