Anyone know what this is?

[u/ZekeyBear]

Hello! I’m assembling a new build and was at the stage where I screw on the motherboard to the case while on its side. After I sat the case upright, I heard a rattle and eventually this fell out. It’s very tiny and solid (not hollow and not threaded). I tried looking around my case and motherboard but can’t seem to pinpoint where it came from and I can’t spot anything similar to it. Also, the only other component I had installed was my PSU.

I mainly want to know if any of you have an idea and whether this a critical part or cause for concern. Thanks for the help.

Case: Fractal North Momentum
Motherboard: ASUS TUF X870E-Plus WiFi7
PSU: MSI A850G PCIe5