Found this when snorkling in Greece about 17 years ago when i was just a kid. Always wondered what it was... Anyone an idea? Almost certainly made of metal and i think it is hollow on the inside.
From a quick search, it is used to control the flow of refrigerant based on its temperature. The tube deforms based on how hot or cold the refrigerant is, and there are contacts on the tube to switches that permit or resrrict coolant flow
Just to add my 2 cents, it's more likely a filter/drier from a refrigerator. Those are much more common, even though a sensor/thermal bulb looks very similar.