Fray Lázaro de Santofimia was a 15th century Franciscan, who was one of the founders of San Andres. He was also sent to Spain to spread Catholicism around the country. He gave food and provided aid to the indigenous tribes that lived in Guano.
He did many good deeds around the area that people thought it would be an honour for him to be buried within the walls of the church so that his soul could always watch over them. It was recorded that he was buried in a jar after being covered in a white powder called 'cal', which kept him preserved until today. He was buried along with a mouse. There were 2 theories that could've explained the reason for the mouse being in the jar - one was because it was thought that the Franciscan was a lonely man and therefore buried a mouse alongside with him to cure his loneliness in the afterlife. Another theory was that the mouse snuck into the jar to eat him alive but got stuck and could not escape.
Earthquake in Ecuador Reveals Bizarre Burial of a Mummy in a Jar with a Little Mouse. (2017, February 20). Retrieved February 20, 2017, from http://www.ancient-origins.net/history-famous-people/earthquake-ecuador-reveals-bizarre-burial-mummy-jar-little-mouse-007579