some old cup and ball BB's with square tapered spindles had a plastic liner running the width of the BB shell to protect the bearings, et.al. from debris. if that's what you are referring to. it can be destructively removed if necessary, IME.

just a reminder, make sure the downtube, seattube and chainstays are devoid of loose ball bearings, they can get stuck and then come loose later. besides being a nuisance to get them out, they can drive you crazy trying to find out the source of the noise.

they can look something like this, when removed. this one has a bit of the accordion about it: