identify this bolt?

[steve1031]

I just pulled into my garage, and saw this bolt on the floor in the rear of my parking spot. It's 25mm long, with 10mm of thread, and the head is 10mm/ 3/8". I searched what little area I could see (by laying under the rear of my car), and looked around the engine area, but didn't see any obvious holes without bolts. (or readily visible matching bolts)

The bolt was quite clean, and the weather in Denver has been snowy off and on the last few weeks, so I don't know if this bolt is from the underside. I tried the search on this site, but didn't find anything like I needed. I honestly have no idea where to begin looking, so I'd love feedback from anyone here.
Thank you,
Steve

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[CoryM]

That bolt is not a factory bolt for any car. That being said, those bolts are often used to hold plastic undertray panels together when the OE ones break or the nuts strip out. And license plate brackets etc. Check the plastic panels under the front of the car for missing bolts. If not, it's probably just road debris.
Cheers.

[Altitude]

License plate bolt. The bolts that hold on body parts are not self tapping.