It's a piece of copper tubing from what purpose one could only speculate. Supply line for fluids off a vehicle/tractor. I have a supply line running from the power steering pump to the steering box on the 45yr old tractor. It's been replaced as the corrosive fluids eat through the copper.
Water will pin hole copper after a decade even, so basically your find isn't "old" in the sense of timeline. I'd put it under 70 yrs old.