Originally Posted by
theblackbullet
hmmm...I think it may be the old tube that caused it to do this. not sure what you mean by standard, but it was a shimano bb-un40 according to bikepedia
OK, what you likely have stuck in there is the plastic non-drive side cup that Shimano uses for many of it's older square taper cartridge bottom brackets. If you remove the non-drive side cup first, the plastic ones often fracture and leave a large part still in the bb threads. You can guess how I know this.
Removal requires a lot of CAREFUL work to slot and break out the remains without damaging the threads. If you aren't comfortable doing this, a trip to the LBS is highly recommended.