They are Austrailian lace nails. You make royal icing lattice pieces on them.
Sounds like you got yourself a boat loaf of great things How come I don't find things like that on Craigslist?
They're vintage "nails" onto which "lace" or cages are piped in royal icing.
A bit of crisco is rubbed on the form, the RI piped in lines over it & allowed to dry. The nail is warmed gently under a lightbulb, or some other minor heat source, and then carefully removed.
I have several of them--but I've never tried to use them. Just no call for that type of work these days.
That's pretty cool though! I've never seen them before...but I love picking up new information.