Is it a dog treat?
Copper piping in a wall, most likely plumbing. If I'm right it's open to anyone!
Im looking for the specific device it is. It is made of copper, but has a specific purpose.
My original post contains the hint
Hopefully this helps, the top of the device is closed and does not connect to anything. The device serves an important purpose.
An accumulator to smooth sudden pressure changes in the water pipes?