What is this? Possible tack or junction?

[RustyRelic]

Found at site that's given a few era items. This has rivets and are hollow and not nails. Maybe a frame and it held something else between the three bent tips? I'm weighing options to see if it's worth cleaning up if it's interesting. Thoughts ..

I still can't figure out why my pictures are loading sideways/upside down

 

[oddballaffliction]

I *think* this is called a 'calk' and was used for traction. That is my best guess!