That looks like a Minifigure, Headgear Helmet Gladiator I wouldn't call that piece rare.


It is definitely possible, since ABS is a plastic that can be either mechanically or chemically affected. Cleaning bricks is a well-studied field, you will find useful information regarding this topic all over the internet, including here. Polishing LEGO bricks is less heard of, but can be done either mechanically (another link) or chemically (another link)....


The new brick separator is smaller, therefore uses less plastic and is cheaper to mass produce, it also means it can fit better into tighter spaces. It has a pusher to remove Technic pins and a chiselled edge to pry off tiles, there is a middle hole in the two female stud connections which allows you to remove 1X2 'jumper tiles'. The additional Technic ...


As the others mention, I don't think it was ever possible. Like the goblet part mentioned above, another possibility is that you were putting them in the sauce pan (#4529) which first appeared in 1983. Scala cups (#33054) will also fit one but they didn't appear until 1997. I think these dates are correct, I know someone will correct me if not :)

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