What feature is characteristic of a cauldron trap?

A cauldron trap is specifically designed as a theatrical feature that is constructed below the stage surface. This allows for objects or performers to appear on stage from beneath, creating dramatic effects and surprise entrances. The design is integral to many stage productions, especially those that incorporate elements of magic, illusions, or dramatic transformations, where the sudden emergence of characters or props is essential to the storytelling.

The option indicating ornate designs refers more to decoration, which is not a defining characteristic of the cauldron trap itself. Supporting actors directly relates more to the construction and engineering of the trap rather than its function as a trap used for reveals. Lastly, while lighting enhances stage visibility in general, it is not a fundamental feature of a cauldron trap specifically. The correct answer emphasizes the unique structural aspect of the trap that sets it apart in stagecraft.