Here's a first...

[Mikey P]

Hopefully the Mr's diamond ring doesn't roll in there

 

[Brian H]

Is it on a crawl space or open basement? At least that way they could take the duct work apart to retrieve it.

 

[Kenny Hayes]

DIYer

 

[Doug Rice]

It's a built in drain for floor cleaners. You wonder how much stuff has been swept into the holes.