>Greek-Egyptian-Roman mysteries are fixated on caves
>pagans loved caves
>everyone said someone lived there (most often reports of reptiles with horns, wolf-like creatures - rakshasas/werewolves, at least two species, and hybrids were also encountered)
>>An angel appears to Muhammad in a cave
>Jesus was buried in a cave, and when he came back to life, no one recognized him.
>Mithras emerged from a cave.
>There's a legendary trope of a hero emerging from a cave (sometimes I think the world tree is underground. At least the Sumerians believed it was) and that many mythical creatures live underground.