In a dark attic's narrowest corner not long ago, I found a pale brick. Something was engraved on it, and now all but indecipherable. The stone felt made to be taken in hand, and its use was a mystery to me.
Now, it turns out throughout the 19th century, several companies in Bridgwater by the River Parrett turned out "Bath Bricks" by the millions. Made of silt from the river bank, the bricks were used around the world to clean floors and doors' steps, and to polish knives or sickles, I guess.
Neither Bath Bricks nor the one I've stumbled upon clean automatically, though, once set up — like Outlook.com does:
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