Someone at my house apparently found it under my car. I have no idea what it is.
I cannot tell you exactly what it is, but I can tell you with 100% surety it doesn't belong on your Hyundai. It looks as though it is a line piercer used in some plumbing operations. The larger screw on the bottom pushes a line up in the curved section, then the top portion is a valve.
It is a water line piercing (saddle) valve. They are illegal in most states.
Do I get a cookie?