As one of the simplest constructs, apprentice artificers are taught how to make these animated stones early on. Petrocks are often given to young conjurers as their first cryture because of how easy they are to acquire. Many non-conjurers even keep them as pets, since they are docile and not hostile to humans, like natural crytures. The faces and decorations are painted on before the animation process, and can move to express the cryture's feelings. These decorations are often chosen by the buyer, but some artistic artificers have their own signature designs or styles that they maintain. If you want to learn more about Crytures, my monster-collecting TTRPG, check out the wiki over here! https://www.worldanvil.com/w/crytures-dicebag