Apollo 13. NASA called the Apollo 13 mission a "successful failure".

Ellipse. A ellipse looks like a circle that's been squashed into an oval in places.

Organs. There are 78 different organs in the human body.

Clouds. Hailstones grow larger as they move about the cloud and collide with rain drops before falling to Earth.

Cell Wall. Cell walls are comprised of specialized sugars called "cellulose".

Vitamin B12. A B12 deficiency in the body cases anemia.