Crypt

From Srafopedia

In medieval terms, a crypt (from the Latin crypta and the Greek kryptē) is a stone chamber or vault, usually beneath the floor of a church or castle, usually used as a chapel or burial vault possibly containing sarcophagi, coffins or relics of important persons such as saints or high ranking church officials.

(Source: Wikipedia)

In the crypt of the Jordan College Oratory Lyra discovered that it was the custom to place a metal disc engraved with a picture, and the name of the deceased person's dæmon, with their remains, which in some cases was just a skull. With this knowledge she was able to improvise a suitable token which she placed in the mouth of Tony Makarios before his cremation, to reunite his body with the memory of his dæmon, Ratter.