The Word of the Day again comes from OPTIC NERVE by Maria Gainza, and this one is so interesting I have added a passage from the novel about it.
Hikaru dorodango are balls of mud, molded by hand into perfect spheres, dried, and polished to an unbelievable luster. The process is simple, but the result makes it seem like alchemy. A traditional pastime among the children of Japan, the exact origin of hikaru dorodango is unknown.
I have never heard of these mud balls or the process of making them but it is fascinating! Here is the passage from the novel,
Since time immemorial, children in Kyoto have been taught to work mud with their hands; sitting together in circles, they take a clump and roll it until it is the size and shape of a billiard ball. They work for hours in the sun, leave the balls to dry in the shade, dip them in water and go on working, however long it takes. Over time the balls of mud transform into polished bronze spheres. Work on the dorodango only a little too much, and cracks appear. The technique is passed down over the generations, only the most tenacious master it.