I was recollecting on some old Tom & Jerry cartoons and began to wonder why mouse holes were often represented like the picture below.
Did it just have to do with the cartoonist trying to personify mice and make it look like they live in houses with doors like humans. Or was it something more, for example perhaps many houses built in those times had holes like the above that were supposed to be for pipes or vents but when unfilled mice liked to take refuge in them. Any ideas?