It's in the "other" section in the menu. So i think it is a key item for something. I can't use it

What does mysterious seed do? I already Finished the game but don't know what to do with it

Thanks a lot. What does sunshine mirror do by the way?

 

I am here and it keep making me wander around. I don't know if it has some kind of code for direction like the star room somewhere else in the game

I get to moon room after beating the sun labyrinth.don't know what to to do in moon room. Help me please.