Block entity

A block entity is extra data associated with a block, beyond the finite set of block states associated with each block.

Usage
Block entities store additional information about certain blocks, with the type of information varying by block. In some cases, this information is used to create a more complex model, such as the book on an enchanting table. In other cases, it is used to store contents of an object. Blocks with block entities can be moved by pistons.

List of block entities
These are the current blocks that hold block entities.