What is a metal or concrete enclosure designed to protect the casket called?

A metal or concrete enclosure designed to protect the casket is called a vault. This structure serves several important purposes: it helps to prevent the casket from collapsing under the weight of the earth or other materials placed above it, offers protection against water and the elements, and contributes to the overall integrity of the gravesite.

Using a vault also provides a level of security for the remains, ensuring that they are preserved in a respectful and dignified manner. Many cemeteries require the use of a vault to maintain uniformity and aesthetics across the burial sites.

The other terms listed refer to different concepts within mortuary practices. A niche is a small space used to hold an urn, while a columbarium is a structure that contains multiple niches for the purpose of storing cremated remains. An urn typically holds ashes, making it distinct from the protective function served by a vault, which is specifically designed for caskets.