How to verify if the apple mice is a real apple product or not since my husband bought it from Amazon. And, I was told serial number is not valid in the apple support.

I want to seek help to verify if the apple mice is a real apple product or not since my husband bought it from a vendor on Amazon. I tried to use the apple support to help me. However, after I put the serial number as Apple support asked for, it showed me that the serial number is not Valid. I am now more worried if my husband just got a fake one.