Unknown Part Found In Bumper

Took off my front bumper end caps today, and the front fender linings as well. Upon doing so, inside the bumper on the passenger side, I discovered a part which I have no clue what it is/ what it does. Since I can't post pics yet, I will try to explain it.

Essentially it is a plastic ball (black) about the size of a softball, with a plastic triangular brace on each side with a place to screw it down inside the bumper. It's located near the passenger side horn.

BTW, I drive a 2001 XJ Sport, stock at the moment, as I'm working to save money for all the goodies to add, as well as work on my 1951 Dodge M37.

Any help would be greatly appreciated.

It holds vacuum and is needed for it to run correctly/your heater controls to work.

Vacuum reservoir. Needed for cruise and dash vents. Plenty of here on it. Try the search function.

Ok, I wasnt sure if it was that or not because I was browsing pictures of stock Cherokee parts, and found a pic of the vacuum canister, but it didn't look like the part I found.

http://www.teamgrandwagoneer.com/parts/Detailed/797.html

Mine was spherical, while that one is shaped like a pill, so idk.

Thanks for the help though.

http://www.ascmclarencoupe.com/Parts/E3SZ-19A566-B_VacuumCanister.jpg
Cliff notes: Yes it is the same

The later models are spherical, the earlier ones are pill-shaped. I think they made the change somewhere between '98 and '00.