(C8H8)n...

…polystyrene

B handed me this little cube so I blipped it (what else?). If I've got the formula wrong, I blame Wikipedia.

R.I.P Pete Seeger. This cube brought back my first memory of him singing 'Little Boxes' (made out of ticky-tacky) when I was about 10. I think it was on the Royal Variety Performance which everybody watched in those days.