And Friends, Ep 16: "Bottle episode"

Site B4 appears to contain the ruin of a kind of primitive kitchen. Most puzzling is the presence of sand in the kitchen and even in the food. We checked whether this was rubble and, no, the arcane bubble protected most of the sites from rubble over the millennia. They seem to have intentionally added sand to their food, or, at least, they did in this city.

- Archaeologist Danell's log, 2337 D