A ciborium is a fancy container that people use to hold special things, like really fancy cookies or important jewelry. It is usually made of precious metals like gold or silver and can be decorated with pretty designs and patterns. It has a lid that can be opened and closed, kind of like a treasure chest. Inside the ciborium, there are usually smaller containers where people put things like cookies or jewelry so they won't get mixed up. The ciborium is often used by religious people to hold special bread called the Eucharist, which they believe becomes the body of Jesus during a special ceremony. So, basically, a ciborium is a fancy container used to hold special things, often for religious purposes.