Beginning a shell grotto - or using up extra mortar

The very first steps towards fulfilling a long held ambition of constructing a shell grotto.  (Or just being me and not wanting to waste anything and being left with a small dish of mortar after a recent Summer Camp mosaic project. )  Garden stones, glass "pebbles" and oyster and clam shells applied at random and at warp speed one hot, humid afternoon.  Hopefully this is just the start of something more ambitious.