The base is fixed the stem inside is round. Also no hole on the bottom.
Plug on right is metal was on top. Bottom appears to be sink. Top part over grove is cardboard or soft lead.
Looks kinda like an old electrical contact, where the wire would be wrapped around the post there. I've seen similar bits on an old telephone switch board I found in the woods.
Hey Dirt Guy .. (and Charlie) I had posted your find here, too, hoping to get some insight into it to help you identify it .
Here is the link to the post.
Good luck!