Where did you find it?

I can't say I have ever seen that in a CX-7 before.

 

It looks like a firewall gromet often used when a hole is drilled for wires or small hoses to protect them.

I use them all the time and keep dozen various sizes on hand in my own garage as well we keep them in the shop. More universal part then a specific OEM but OE does use them. Good luck with your "easter egg" hunt finding where it came from. I will say because your picture does not show a separating side, I am doubtful it is nothing more than a part that was left by mistake.