Secret
It is the displacement method.
It would be hard to find a line of symmetry on a moon, as it is likely to be irregularly shaped.
Google "Archimedes' Principle" and see if that gives you a clue...
Mass divided by Volume = Density. Or use the displacement method for an irregularly shaped object.
The apple was irregularly shaped
The volume of an irregularly shaped solid can be measured by placing the solid in a known quantity of water in a container with measurement markings. Take the new volume and find the difference between this and the old volume. This is the volume of your irregularly shaped solid.
batholiths
Finding the center of gravity of an irregularly shaped object can be done using the plumb line method.
Poikilocyte
square
batholiths
Lump
A lump
Tight
a sharply elevated, irregularly shaped, progressively inlarging scar
Frank Stella.