Final answer:
The vessel used for exposing the Blessed Sacrament is called a monstrance, an ornate vessel significant in Catholic liturgical practices for the adoration of the consecrated host.
Step-by-step explanation:
The vessel used to expose the Blessed Sacrament for adoration is called a monstrance. This sacred object is of great importance in Catholic tradition, particularly during the practice of Eucharistic adoration where the consecrated host (believed to be the body of Christ) is displayed.
The monstrance is often an ornate, sunburst-shaped vessel, designed to hold and showcase the Blessed Sacrament for the veneration of the faithful. Its purpose is not only for display but also to signify the presence of Christ and to inspire worship among the congregation.
In the context of Catholic liturgy and architecture, like that of the San Vitale church in Ravenna, Italy, these religious artifacts play an integral role during ceremonial processions and the celebration of the Eucharist, reflecting the ritual functions illustrated by the mosaics and artwork within the church space.