The Squinkies - Surprise Inside set of Happy Meal® toys consists of 16 small figurines each inside a pop-open ball.
The figurines measure approximately 3.5cms tall and the plastic balls measure 5.5cms in diameter.

The toys were released in four different series over four weeks:

Ocean Theme - Seahorse, Fish, Crab, Mermaid - in turquoise balls.
Pets Theme - Puppy, Bunny, Kitty, Frog - in purple balls.
Zoo Theme - Monkey, Lion, Elephant, Polar Bear - in green balls.
Fantasy Theme - Fairy, Dragon, Pegasus, Unicorn - in pink balls.