While observing rats in a maze, patrick realizes that the rats are able to find their way to the end of the maze even though they are not rewarded at any point during the experiment. this type of learning can best be defined as?

This type of learning can best be defined as latent learning.
Latent learning is a type of learning which a person (or in this case, an animal) exhibits unconsciously, without actually acknowledging that the learning has taken place. Another important detail to note here is that this learning happens regardless of whether or not there is an incentive or a reward present. 

The one that most represents the earths mantle would be the skin since the mantle is the upper part of the earths depths which is just like the skin of an apple.