Mimicry: Please help me understand how

The evolutionary mind has evolved some common set of defence strategies. When a under threat do this or do that.(there is a long list)
A mouse will hide inside his hole. And so do others animals of its kind which live under the ground like rabbits.
Given a small size make it look dead or pretend to be another case of
a natural event like falling seeds or bird falling or leaf falling ..Mimicry is common ot all small species of animals.