The exagram (Eg) is a unit of mass in the metric system. It is equal to one quintillion (10^18) grams. The exagram is an extremely large unit of mass and is primarily used in scientific contexts when dealing with colossal quantities of matter, such as in astrophysics or geology.
To give you an idea of the scale involved, one exagram is equivalent to 1,000,000,000,000,000,000 grams or 1,000,000,000 metric tons. This unit is rarely encountered in everyday life but is valuable when measuring the mass of massive celestial bodies, geological formations, or other incredibly large objects in the universe.