These are the small 0.01uF or smaller capacitors with transparent edges and you can see
foil in the innards? If so, I think you are talking about "polystyrene
capacitors". Yes, they were extremely popular in UK/EU for at-chip decoupling
capacitors in the 1970's and 80's. They are not polarized.
I'm not sure why polystyrenes were so popular for bypass/decoupling in EU and not so
popular on this side of the pond. Here in the US we were more likely to see polystyrene
in audio filtering/coupling locations where the cheapest ceramics had odd piezo properties
and low leakage of polystyrenes were desirable. I do remember seeing polystyrene bypass
capacitors on at least a few DEC boards of the 70's so they did make some inroads.
There are real glass capacitors used where zero leakage and zero soakage are
uber-concerns.