score:5
It's called an ablution cup:
It's a vessel of water the priest uses to purify his fingers of the Sacred Particles after he touches a consecrated Host outside of Massβe.g., after he obtains Hosts to place them in a pyx for sick calls, or after he distributes Communion outside of Mass. The priest submerges his fingers in the water and makes sure all the Sacred Particles are dissolvedβsimilar to the ablutions ceremony at the end of Mass, where an altar server pours water over the priest's fingers into the chalice. He then dries his fingers with a purificator.