Geometric shapes, such as triangles, are non-Unified Modeling Language (UML) elements that you can use to add visual interest and provide additional information for a UML diagram.
A geometric shape is not part of UML notation and represents only a basic shape. Therefore, geometric shapes are not associated with any UML element in a diagram and do not have any UML semantics.
You can also add text to geometric shapes in UML diagrams to provide additional information.