There is a solid metal line coming out of the ground right next to the gas line for the pool heater. So that makes me think it has something to with the gas line plumbing. The line also has that greenish battery acid stuff at the base where the line meets the earth. So does that mean it's an electronic component, perhaps a ground for something? I'm hesitant to just dig it up without knowing what it is or what it's for. Any suggestions?