Worksheet investigations: what can an owl pellet reveal about diet? answers

A pellet is the regurgitation of things that the owl could not digest.  From studying the bones and fur of the pellet a scientist can learn what type of animal the owl is eating.  The relatively weak stomach muscles of the owl form the undigested fur, bones, feather etc. into wet slimy pellets. In this process even the most fragile bones are usually preserved unbroken.

They both have rock surfaces

No they’ve not done that