An olla is a ceramic jar, usually with a short wide neck and a wider belly. They can be used for a number of purposes, from cooking soups or stews to water and food storage.
Clay ollas have been used for centuries by Indigenous peoples of the Americas as a means of keeping water cool. When an unglazed olla is filled with the water, the water permeates the clay walls of the vessel, causing the olla to ‘sweat’. The evaporation of the sweat cools the olla and its contents.