It sounds very obvious, but there are some macroscopic medical phenomena that apply only to mice and small rodents. For example, I recently learnt that you can

It sounds very obvious, but there are some macroscopic medical phenomena that apply only to mice and small rodents. For example, I recently learnt that you can freeze hamsters and then "thaw" them in a microwave and they'll just wake and continue to live normally; this doesn't seem to work with humans unfortunately. Just imagine the applications, you wouldn't even need a regional hospitals; just freeze everyone and send them to a centralised mega hospital and ship them back when healed. (As an aside, this was one of the first ever uses of a microwave.)