A crucifix
A crucifix was a religious icon denoting the Christian religion on Earth. It was an image, often a carving, of Jesus Christ being crucified on a cross. (TOS: "Bread and Circuses")
A crucifix was present in the Leonardo da Vinci's workshop holoprogram. (VOY: "Scorpion")
Seven of Nine studied a crucifix while contemplating spiritual experience. (VOY: "The Omega Directive")