They stack nicely when put on one another properly. I am stuck on the material they are made out of. I will try to clean one up this weekend and see if by any chance they are so dirty they might be hiding the shine of Bakelite but I think a little heavy for that. They did seem to chip a bit so maybe a composite material with clay.
Now at least I know what they are. I can go donate them back and mark the bag properly.