Monstrance clock

The monstrance clock, or mirror clock, is a type of clock that was developed during the Renaissance (1300 AD – 1600 AD). It is cross-shaped and typically either gold or silver in colour but can feature both colours. They used to play an important part in a church ritual and often incorporated sacred figures as part of the design. The clock made use of a rotating ball at the top or in the base to indicate the time of day. Monstrance clocks and crucifix clocks remained fashionable until the eighteenth century.[1]

A Polish monstrance clock

Pop culture references include the song "Monstrance Clock" by the band Ghost. The song itself has themes of satanic ritual, rather than Renaissance-age Catholicism.