story ideas for grabs

i have decided that ill post random ideas here for stories that anyone can grab. i will post them as i think of them. and if you are going to use the idea, post here (or pm me your thoughts if you want).

one idea is of the caves under canterlot. it is canon that those caves are there. and the only thing really known about them is the crystals.
what if those crystals are there to keep others from finding what is hiding in them... i mean that cave is really hard to navigate due to those crystals and who knows what else... sounds like something IS hiding there... what tho? thats up for others to think about if they use this thought.