What material was the shelter made out of inWorld war 2?

During World War II, shelters were commonly made from various materials depending on their type and location. Anderson shelters, for example, were constructed from corrugated steel and were designed for use in backyards, while Morrison shelters, intended for use indoors, were made from steel and reinforced concrete. In urban areas, air raid shelters were often built using brick, concrete, or other sturdy materials to withstand bomb blasts. The choice of material aimed to provide maximum protection against aerial attacks.