Stone that rings like a bell
Its called a Lithophone (who knew). Just to the west of the Military Road above Gairnshiel Lodge is a layby and a lithophone. If you give the stone a whack with a stone it rings.
Now don't get your hopes up. It rings like a hollow stone not Big Ben. This particular stone may have become popular during the Victorian times. Queen Vic heard a few pieces played on stone instruments, and since she lived just up the road in Balmoral may be it caught the locals ear.
Worth a look and a bash, but only if you're passing.