The Catechism of the Catholic Church (paragraph 701) states, At the end of the flood, whose symbolism refers to Baptism, a dove released by Noah returns with a fresh olive-tree branch in its beak as a sign that the earth was again habitable. When Christ comes up from the water of his baptism, the Holy Spirit, in the form of a dove, comes down upon him and remains with him. The Spirit comes down and remains in the purified hearts of the baptized. In certain churches, the Eucharist is reserved in a metal receptacle in the form of a dove (columbarium) suspended above the altar. Christian iconography traditionally uses a dove to suggest the Spirit.