The Megalodon, which went extinct millions of years ago, was the biggest shark ever documented. The Megalodon was probably not as big as you think, but is most likely stronger than you could imagine. Judging by the size of its teeth, the Natural History Museum in London believes that the shark could have been up to 60 feet, while others think it can grow up to 80 feet. The largest tooth ever discovered was 7 inches which leads you to believe that it is totally possible to be 80 feet. To give you an example 7 inches, it is about this long:

|                   ||                   ||                   ||                   ||                   ||                   ||               |  With a tooth that big, the jaws have to be several times bigger because sharks have many rows of teeth. Imagine getting bit by a jaw that is 7 feet tall and 6 feet wide that has the bite force of 40,131 pounds per square inch. That,s why this predator was the king of the ocean during its time.

https://www.livescience.com/63361-megalodon-facts.html

Scientists and engineers have worked on discovering how this shark survived and functioned based on a couple of fossils. they determined its diet and even its habitat.