In one of the volumes of the library of the Franciscan monastery in Şumuleu (Aurelius Augustinus: Epitome omnium operum. IV. Köln, 1539), our former colleague, the retired museographer, Erzsébet Muckenhaupt found the following mention: "Az zereda uarat kezdek epetteni 1623, 23 di( e) Aprilis". Based on this record, the start of Mikó Castle’s construction can be dated to April 23, 1623. The April’s object of the month was chosen to mark the opening of Mikó Castle's 400th anniversary year and it is a masonry heater’s tile depicting an angel's head, dating from the beginning of the 17th century, which was discovered during archaeological excavations in and around the castle.

Several fragments of this specimen were discovered in the upper part of the well (more precisely in the filling made during the widening of the upper part of the well in the first half of the 18th century), respectively in the filling of the ditches of the fortress. Both unglazed and green or brown enamel specimens were discovered. The stove was not only used for heating, but its designs and decorations made it one of the most prestigious ornaments of the rooms.

Being made of clay with fine paste and sand, modeled by pressing in cloth pattern, oxidizing and complete firing, and the others with plumbiferous enamel.

The tile is square, with a short leg and a simple frame. The decoration was made in such a way that in the central space of the piece there was an angel's head (seraphim) with four wings, with a small crown on its head and a string of pearls around its neck. In the four corners of the tile are placed angel's heads with a crown on the head and with stylized open wings, oriented towards the center. The side fields are decorated with pairs of baubles.

Two similar specimens are known: a specimen with green enamel from the collection of the Brukenthal National Museum in Sibiu and a specimen with brown enamel from the collection of the Romanian National Museum in Bucharest. In both cases, the origin is indicated as Brașov, which makes it likely that the stoves were ordered from the Brașov potters' guild by the commander of the construction of the fortress-Mikó, Mikó Ferenc from Hăghig.