Scientific law.
A scientific law describes something in nature and predicts how it will behave without explaining.
This is because before a scientific law has been made, numerous observation has been done under different situations. The scientific law is established when a natural event invariable occur given a set of circumstances.
Trilobites are found worldwide and evolved rapidly, making them easily distinguishable from trilobites of other time periods
I'm not sure but I thinks the first animal that produce bacteria is Pig.
Rotator cuff
The rotator cuff is a group of muscles that perform a variety of tasks such as flexion, abduction, internal rotation and external rotation. The muscles in this group are essential to all movement of the shoulder, making them very essential for upper body mobility. Namely, the muscles of the rotator cuff are supraspinatus, infraspinatus, teres minor and subscapularis.