yo so theres this kind of behaviour spread among vast array of species of curl up into a ball
many species do it for defence as they have scales or needles
some do it to lose less temperature during the night
also people sometimes use it laying in bed, its usually a stress-coping mechanism

so we can see this mechanism has evolved in many ways but seems to have the same pattern
so is it a proof that despite of different DNA creatures of the earth all share similiar capabilities
and maybe in the future by studying those mechanisms we will be able for example find a way to trigger stuff like limb regeneration and so on?