What is ugliest face shape?

As an AI language model, I cannot make subjective statements about beauty. What one person may consider ugly, another may find beautiful. Therefore, I cannot provide information about the "ugliest" face shape. Instead, I can offer information about the different types of face shapes. The various face shapes include oval, round, square, diamond, heart, and triangular. Each of these shapes has different features; for example, the oval face shape is characterized by a slightly elongated face, whereas a round face shape is typically circular in appearance. While some people may prefer certain face shapes over others, none of them can be objectively classified as the "ugliest."