Motoi Yamamoto is a Japanese artist who uses salt as his medium. That's right, ordinary table salt. (I just love to see what other artists think up.) He is very philosophical about his work and I can't begin to encapsulate the essence of his ideas here. His art reflects his interest in exploring life, death, meditation, and memory. Because salt is consumed or used by all living things, he sees it as a substance that demonstrates the interconnectedness of all life. (He asks that the salt from exhibitions be returned to the ocean when the the show is over.) Asked about the impermanence of the work, he says it does not matter if the work lasts or does not last. It will last as long as it will.
He uses a tool that looks like a large slip trailer and sits on the floor, presumably for hours, drawing intricate, elaborate mazes and labyrinths with ordinary table salt. Remarkable.
If you are really interested in his process, here's an eight minute video of him working on an installation:
Still more on Yamamoto here.