Look at the average moon, and you see a battered, bruised face. Look at Europa, Jupiter's fourth-largest moon, and you'll see the unworried image of youth. Even when Europa's surface shapes are strengthened by shadows, it's still strangely smooth for a solar system satellite. Compare Europa to Mars, which has 450 craters larger than 100 kilometers in diameter. Blast Europa with an asteroid, and it will absorb the shock without forming much of a crater.
Pucks are resilient because they're made of rubber.
Europa seems to be resilient because its smooth surface may rest on a giant subterranean ocean. Wedge-shaped structures that resemble junctions between Earth's crustal plates at the ocean floor. If the ocean hypothesis is correct, Europa is built in layers. Since we already know that this moon is coated with frozen water and is not dense enough to be pure rock, the photos support the notion that Europa also contains water inside. Make that liquid water.