What are other things with curve?

Many natural and man-made objects feature curves, such as rainbows, the paths of rivers, and the contours of hills. In architecture, curved structures like arches and domes create aesthetic appeal and structural strength. Additionally, in technology, the design of ergonomic tools and devices often incorporates curves to enhance comfort and usability. Curves are also prevalent in art, music, and literature, often symbolizing fluidity and emotion.