An aside that may interest:

I live in a "heritage" farmhouse (a.k.a. endless fixer-upper). When I first moved in, I found several large, smooth field stones in the basement. They had obviously been kept on purpose and used for something, so I didn't throw them out.

It took me a while to figure out what they were: they're "kraut stones," which would have been well-boiled and then placed on top of the freshly made sauerkraut to keep it below the level of the brine for proper curing.