1996 E320 Road debris damage: TRW PP TV 20?

[AnthonyA]

Does anyone know what this little black piece of plastic does? It's marked TRW PP TV 20, is approximately 2 1/2" L x 1" H x1" D, and has a black pin about 1" in diameter. I have a 1996 E320 that sees limited street time, and usually only on nice weather days (I live in New England). The other day while driving through some street construction, I hit some debris that broke the splash guard so badly that I needed to remove it. This does seem to cause a problem, but I also broke off this little black plastic piece. The car seems to drive normally and I do not notice any differences (rattling noises or leaking fluids). Is this part of the splash guard or something more critical? Any info is greatly appreciated!