Places that you can check, check behind and around:

refrigerator, stove, dishwasher, washer, dryer, dressers.

Those are places that stay dark. Then you can check under sofas and beds. What you can do if you know somebody that has a snake camera that has a light so you don't have to rip the bottom cover thing. The snake thing can go in and look around.

Also your lower cabinets have holes in them so it could be under the cabinets. This snake cam thing they use to like go down clogged drains will be able to check all those spots.