SECO is a large highend tool manufacturer, I use a good deal of their inserts for lathe work and a considerable number more for face milling applications, excellent tools but a bit pricey for hobbyists I suspect.
Possible they were just tossed in an old SECO tool package when they went out the door after years of use, most ejector and core pins have one particular mold that they fit.
They may be worth a good deal to someone that currently owns the molds that they were made for, often design changes in a product will send such tooling into the scrap bin. Even with the miraculous thing that is the internet you may never find what their original use was.
Could have been ejecting diecast aluminum/zink Academy Awards or casting common household utensils, you will likely never know.
About the size of 5C.
May have been made for one particular multi part job, one never knows, I have a drawer full of tools that I made 20-30 years ago that I haven't a clue what they are for, memory fades over time. I now toss such tools in the bin if I do not have the good sense to mark them.
Which I do not for the most part (-:
This was when I worked for myself, at the small shop where I currently work the Owner insists that when I make a tool or fixture that one of the mill operators engrave it with a number, I do this about 1/2 of the time, pisses him off to no end.
I would guess they are transfer punches made from die pins. We used to modify pins like those and use them for cleaning excess plastic from die heads and/or transferring a hole pattern to a new piece of Inconel or 316 stainless.