Without seeing a pic I'm somewhat guessing here, but is it the piece that is right by the headlight assembly?
If so, I believe it is a protective piece of rubber to keep out what you don't want in the engine compartment and if I'm not mistaken (without being right in front of my JEEP now) it has an opening that has an X cut into it right?
This is where folks have been running their custom LTT cold air intake after removing said rubber piece.
I'm not sure exactly what other functions this provides, it might be somewhat of a matter of just "hiding" the things behind it.
Pics always help identify things

_________________
"The power of imagination makes us infinite" - John MuirDD Ride03 Limited KJ
Toy: 1961 Ford Fairlane
http://www.cardomain.com/ride/3182277 Current Mods: Surco Safari Rack, K&N Filter, Curt Hitch, VR3 HU, Optima Yellow, Frankie II Prem & JBA's Gen 4.5 UCAs, Skid Row t-case skid, and more!
Coming soon:???