* The unfurling frond of the silver fern (ponga): This is the most prominent inspiration for the koru. The tightly curled frond represents potential and the journey of growth.
* The spiral of a new fern frond: The spiral shape of a new fern frond, as it unfurls, mimics the koru's design. This represents the continuous cycle of growth and renewal.
* The spiral of a nautilus shell: The nautilus shell, with its intricate spiral, is another natural form that inspired the koru. It symbolizes the journey of life and the connection between the past, present, and future.
* The swirling movements of the ocean: The ocean is a powerful and constant force in Māori culture, and its swirling currents and waves may have also inspired the koru's spiral form.
These natural forms, with their inherent patterns of growth and movement, contributed to the development of the koru as a powerful and meaningful symbol in Māori art and culture.