Hi all, I am new to this forum and this is my first post. I hope some folks can help me out. I am in the US military stationed in Belgium working for NATO. My wife and I are renting a house here that is heated by oil. The oil delivery company told us that we needed to add a whistle to our...

I was wondering if anyone knew what the attached picture is? It is buried in the ground directly behind a house built in 1955 in Florida. I think it might be the lid of an old oil tank or septic cover, but am not sure. Any ideas? Thanks, Lawrence