Antique pectoral crucifix used onto rosaries and the larger models are also applied on walls. They became popular in Northern Europe since the 18th century. Below is the skull & bones symbol. Which may refer to the Mount Golgotha in Jerusalem, where Jesus was crucified. But the skull & bones also represent the Momento Mori. Which symbolizes Jesus’ victory over death with His resurrection. This particular crucifix here is dating from the 19th century.