What visual indicator shows that an object is a prefab variant in Unity?

In Unity, a prefab variant is indicated by a blue cube with a shaded face in the Hierarchy or Project window. This visual cue signifies that the object is a variation of a base prefab, allowing for unique modifications while still retaining a link to the original prefab. This relationship makes it easier to manage and create hierarchical structures of prefabs, facilitating changes across multiple prefabs while allowing for customization at the variant level. The specific blue color and shading help distinguish prefab variants from regular game objects and other types of prefabs, providing clear visual differentiation in the development workspace.