Cruets, small, usually glass, vessels, are a sacred object used in Catholic worship. Typically paired, they hold wine and water, used in liturgy during the Eucharistic celebration. One contains wine, representing the blood of Christ; the other, water, symbolizing his cleansing grace. Their simple design belies their profound symbolic meaning. The pouring of these elements into the chalice signifies the union of Christ's sacrifice with the faithful. Their presence is essential to the proper conduct of the Mass.