Understand:
What matters is what causes the moon to be lit. It is not a luminous rock, that's ridiculous. It is part of the dome that covers the Earth, and the migratory route of the animals that live on the dome. Do you think life could only reach the floor of the disc? Climbing is easy. They live in darkness, so they remain lit. They move in a predictable path, a migration, and aren't all lit at once. We see the same group, which is why it looks similar, but different aspects light up at different times. Lunar eclipses are probably mating season, or some equivalent.
There is no moon per se, disc or otherwise.