Last week, with the help of findagrave.org, I located the graves of my fourth great-grandparents, which just happened to be located on some private property in Caldwell County, Texas. The owner of the land was very courteous, let me see the graves, and gave me this rusty object resembling a belt buckle, which he said "my ancestors probably touched" and that he found it on the ground on his ranch.

I doubt it belonged to my ancestors, since the ones in question only lived in Texas for less than 10 years, but I would still like to know: What was this object used for, and about how old is it?