What is described as a container designed for placement in the grave around the casket?

The outer burial container is designed specifically to provide support and protection to a casket after it has been lowered into the grave. Its primary purpose is to prevent the ground from settling and to maintain the integrity of the grave site over time. This container can be made from various materials, including concrete or metal, and serves not only as a protective barrier but also as a means of enhancing the overall aesthetics of the burial site.

While caskets are meant to hold the deceased, they do not provide the structural support needed in the grave. Alternative containers might also serve to enclose the body but lack the robust design and support features of an outer burial container. Grave boxes, though similar in name, are typically enclosed structures designed to hold a casket and may or may not be used in combination with an outer container. Thus, the outer burial container fulfills a specific function that aligns with the context of the question, making it the correct choice.