Anybody know what this is?

[SNations]

Do any of you guys know what this is?  This is a kitchen cabinet underneath the second (prep) sink in a very large kitchen in a very large house.  It's a rectangular plastic piece that's screwed down at all four corners.  The scalloped edge is part of a hole that goes through the cabinet bottom to the kitchen floor below.  My first thought is that it's part of a system to turn on the sink with your foot that hasn't been completed.  

Thanks

Steve