Nucleus Solar System

Example:

Imagine trying to find your keys buried under a pile of clothes in your messy room. Just as your keys are hidden beneath layers of clothing, the solid inner core of a comet is surrounded by layers of gas, dust, and ice. In both cases, the essential part—whether it's the keys you need to leave your house or the core of a comet that scientists study—is concealed beneath outer layers that must be navigated or removed to understand or retrieve what's inside.