Snail Graveyard

I was reminded about all these shells, whilst on the subject of snails here.  Recently I visited a local quarry, now disused, so I could take some photographs.  My idea had been to get a good atmospheric quarry image for my page on Facebook.  

Old quarries, where stone is no longer extracted are beautiful places.  Nature very soon takes over and they become quite special environments for wildlife.  In this quarry, large areas of stone were covered with a thick layer of moss, and small alpine like flowers pushed up through rubble piles.  There was a lone, weak (what looked like) red-current bush. All was blissfully quiet, with the occasional call from a bird of prey and the clatter of wings.

I saw an area which I thought perfect for my picture, and as I went about setting up the camera I found I was 'crunching' as I walked about and moved.  On looking closer I noticed that the whole area was covered in snail shells - empty ones - as if this was the dying place and all these snails had come here to their mass burial site.

Do they do that?  Or have they just found something very tasty to eat which turned out to be poisonous?  Maybe they all gathered to hibernate in what seemed like a good place, but it became too severe in the winter. It isn't something I've seen before.

I also found a lump of stone with extraordinary crystals in it, presumably they got trapped as the limestone formed millions of years ago.  What amazing shapes they've made.