Let me quote the German Wikipedia here: "A *Petschaft* (seal matrix) is a small stamp made of hard material; its mirror-image engraved face is pressed into a soft, hardening substance (such as wax or sealing wax). It is used to authenticate a sender's identity on a letter or to signify the seal holder's approval of a document." These seals were primarily used for letters and other documents, rather than for other types of objects. Over the years, I have found six of them in various locations. The two oldest date back to the Middle Ages, while the most recent is from around 1900. Two belonged to craftspeople, one to a nobleman, and one bears a house mark. Of the six, four are well-preserved, while two are in poor condition. The seals are kept in a display cabinet at my parents' house; next time I visit, I can post photos of the others here.