BlockEntity

A block entity is an entity that exists as a companion to a block, so that block can store information that would violate the functionality of blocks on their own.

Despite the name, however, these do not behave anything like regular entities. They do not actually exist to the end user, cannot be seen, and only exist to hold data that blocks cannot.

These used to be known as tile entities, for all of you folks who remember those days.

Inheritors