One of the first things I made when I began poking at my clay was marbled beads. Even then I thought, “Wow, those are like nifty rocks.” Later, I found you really could make faux rocks just about the same way by paying attention to the colours. The addition of small amounts of inclusions – salt for roughness on the outsides, finely ground herbs, glitters, bits of grated clay, sand and such – could really add to the reality. A nice sanding for a smooth river rock or a gritty texture made from salts or the edges of other rocks.
Lucy uses her faux rocks to make a neat little planter for succulents. The use of the bowl as a former for the rocks while they cure is a great idea.