A serdab literally meaning "cold water", which became a loan word in Persian for 'cellar') is an ancient Egyptian tomb structure that served as a chamber for the Ka statue

Ka statue

A ka statue is a type of ancient Egyptian statue intended to provide a resting place for the ka, or spirit, of the person after death. The ancient Egyptians believed the ka , along with the physical body, the name, the ba , and the šwt , made up the five aspects of a person.After death, the...

 of a deceased individual. Used during the Old Kingdom

Old Kingdom

Old Kingdom is the name given to the period in the 3rd millennium BC when Egypt attained its first continuous peak of civilization in complexity and achievement – the first of three so-called "Kingdom" periods, which mark the high points of civilization in the lower Nile Valley .The term itself was...

, the serdab was a sealed chamber with a small slit or hole to allow the soul of the deceased to move about freely. These holes also let in the smells of the offerings presented to the statue.