true but obsidian is more commonly known as volcanic glass.. not a rock as such. It's called obsidian because it's generally black but can be brown or red. It forms from a rhyolitic magma if I remember correctly. Not necessarily smooth.. if it's fractured it can be quite sharp and irregular, it's only smooth because it's frozen lava essentially. It's the reason that when people walk over cooled lava flows it sounds like their walking on broken glass... cos they are.youkokitsune106 wrote: In nature, obsidian is a black colored igneous rock, that is smooth and hard. So it could mean a butterfly made out of obsidian... (though i highly doubt it)
and as to the question... I dunno, I've seen RahXephon and I can't recall it. Still remember..*spoilers*
Ayato's memories have been altered so it's probably still a reference to memory as Rubyeye said.
*end spoilers*