A mouse (plural: mice) is a small mammal belonging to the order of rodents.

My little nephew Eirik and my sister Linda joined me for lunch at my apartment this Saturday.

I don't have a lot of toys, but I do have a little plastic fox and a bob cat.
Eirik played with the little plastic fox. The fox moved into my hallway drawers, and in there it lived as a happy little fox, but Eirik stated firmly in a high pitched voice that there might be mice.

It seems I have a mice invasion on my hands.