TED-Ed: Can you solve the alien pyramid riddle? | Henri Picciotto

A group of scientists discovers a subterranean city on Mars, losing contact with Earth. They explore three pyramids, using algebra to solve puzzles and open a sealed pyramid. Inside, they learn about an ancient civilization that moved water underground. The city itself is a giant pyramid, and solving the final puzzle reveals a lever that could bring water back to the surface.

What engineering marvel did the civilization use to reserve the planet for themselves?

What dilemma does the protagonist face at the end of the exploration?