old key

Hi. Was out for a few hours with my Equinox, here in the UK on a local farm permission....dug this bid heavy key up in the middle of a field. It was a deep one, prob 10"+ easily. Just wondering if anyone would know how old it is and what it would have been used to open? Weird how the teeth...

Found this key in the Parma city neighborhood of Ohio. Stayin at an old 1918 farmhouse near the old Pleasent vally lake park. Sure did get my blood pumping. My first BIG find. Detecting is definitely my new hobby.:headbang::skullflag: Rich