I am trying to create an art project. I recently discovered the art of Bonseki - a Japanese art of creating semi three dimensional landscapes using black lacquer trays and white sand. I want to try doing something like this using edible products - salt, sugar, etc. What I still need to figure out is what I can use that looks like rocks.
What food / edible item would look like a rock. Preferably grey tones (fits with the black and white theme). Rock candy came to mind, but it is a bit crystaline, and usually bright colored. Potatoes seem too brown. Any other ideas?