For decades, scientists have speculated that Europa may be the only place in the solar system with a large amount of liquid water besides Earth. Because the surface photos of Europa are similar to the photos of ice on Earth's oceans, and the ice shell is full of potholes left by various meteorite impacts, many scientists speculate that under Europa's ice shell there may be the largest liquid water ocean in the solar system, and there may be single-celled life under the ocean. And this "life possibility" theory is the core of the movie "Europa Report".