Built-in jar opener
Here’s another kitchen-themed mystery for you. The OP found a plastic object with teeth on two sides, one of which was made entirely out of metal. It looks like you could scratch yourself if you accidentally stuck your hand or finger under there. What gruesome purpose does this sharp contraption serve?
The mystery was solved within the first couple of guesses. It turns out that this thing that looks like it could tear your skin open is used to tear lids off of jars. You’re supposed to push the jar’s lid toward the point where the two sets of teeth meet then twist the jar until you hear the satisfying sound of breaking the vacuum seal.