curve

1. circle

1.1. ball

1.1.1. round

1.1.1.1. clock

1.1.1.1.1. plate

2. football

2.1. oval

2.1.1. curved point at front

3. basketball

3.1. round

3.1.1. shpere

3.1.1.1. curved lines

4. baseball

4.1. round

4.1.1. shpere