This design is an example of form, but more specifically, naturalistic form. Naturalistic is when the design is derived from anything in nature, or a human figure. This particular form is a human figure, which makes it a naturalistic form.
Seated Guanyin Bodhisattva, Guanyin is the Bodhisattva of Infinite Compassion who appears in many guises, in this case as the Water and Moon Guanyin. He sits on rocks by the sea, in the position known as royal ease.