[martin_fierro]

Calcium, in particular, is found deep inside Earth. So if the Moon has a lot of calcium, then perhaps it is made of material that was once inside our planet.

Or else the moon has bones.

kidding.

[DonaldC]

So if the moon was ejected from the earth, why is it so round. Wouldn't it be chunky or odd shaped like an asteroid?

[SlowBoat407]

Or else the moon has bones.

Dammit, Jim! I'm a doctor, not a moon shuttle conductor!