Another UIJ. Unidentified iron junk. Piece of old machinery, this stuff is all over the place. Most of what we dig is junk, there is much more trash in the ground than good stuff, but if one doesn't dig some junk one will miss some of the good stuff. You don't say how deep this thing was or how large it is, but it could have been masking a nice silver coin or a ring or something else cool so it was good you dug it out of the ground no matter what it is. ALWAYS re-check your hole after recovering a target like this just in case there was something else in the hole.