What bug?

[2QuarterPints]

Trying to identify a bug. I pulled the toilet paper roll this morning and about 10 little black bugs shot off, at speed, in every direction. They were probably just under a quarter inch in length, and came out from under the toilet paper cover. Fortunately, a tin of bug spray was in reach so they didn't get far! When I investigated, inside the cardboard tube was a very brittle, black, "pod" and I assumed that the bugs must have come out it. The pod was probably about three quarters of an inch in length. I can't see any others anywhere, but have only had a quick look so far. Depending on opinions of those who may know their bugs better than I do, I may decide a more thorough search is required!