What are some natural occurances of circles in nature?

Question

I need to know 5, and I already know 2:

-the aftermath of a water droplet falling into a body of water
-the moon

...the sun isn't REALLY a circle... and I can't think of anything else...

Answer 1

1. Hail stones
2. Tree trunks.
3. The Earth.
4. Some sea shells, like a sand dollar.
5. Crop circles.
6. A beam of light.
7. Hair.
8. Eye balls.
9. Snow flakes.
10. Snakes and worms.
11. An atom.
12. Many fruits and nuts
13. Some seeds.
14. A circle around the moon

Answer 2

the earth, the centers of flowers, citrus fruits, craters

Answer 3

the core, pearl