Metal Detector beeping but no item found?

[goodcookie777]

I'm in the Laboratory with the Metal Detector and it keeps beeping but I can't figure out the reason why. I swear I searched everywhere for a coin/key but can't find anything... Here's a link to some screenshots of the area that the metal detector is beeping around (it appears when I get closer, but I took screenshots from a distance to get more of the surrounding area): photos [drive.google.com]. I'm curious to know if I somehow missed something/it's a bug, but if it's a secret, please don't spoil it, ty!

[Talzor]

It's probably something in a different room. The metal detector is proximity based and not blocked by walls.

[Inglourias]

There might be a tool you can pick up. It beeps for those too.