Correct me if I'm wrong, but it looks like a rusty screw with an Allen head. Maybe the previous owner had it holding something to the bumper? Check the other side of the bumper and see if anything is attached by it. I'd personally remove it given it's rusty and is also located in a place were a hole is probably not too noticeable.
You are correct sir! I'm going to try to get underneath this weekend to see what's going on behind that bumper. You're right I may just take it off. If it's too noticeable, I can always plug it back up with a nice shiny screw!! LOL
2012 Kizashi CVT AWD/ w paint chips
Orange County/Brooklyn NY
I 'd plug it with a small black rubber plug. If you sanded it a bit, you might even be able to get touch up paint to adhere to the plug, might be almost invisible then.
It looks to me like it's a James Bondish type oil sprayer to blind and cause the driver behind you to lose control. Do you have an extra button on the dash?