This will be Carrey's second trip into the world of Dr. Seuss after his stint as The Grinch in How the Grinch Stole Christmas. This time he plays Horton, the elephant who knows that a person's a person, no matter how small marking his first time voicing an animated character.

Carell recently voiced the squirrelly squirrel in Dreamworks' Over the Hedge and will take on the mayor of Who-ville, a distinguished figure of a very small size, too small to be seen by the elephant's eyes.

Jimmy Hayward and Steve Martino are directing from a script adaptation written by Cinco Paul and Ken Daurio.

THR describes the story saying Horton is about an imaginative elephant who hears a cry for help coming from a tiny speck of dust floating through the air. Suspecting there may be life on that speck and despite a surrounding community that thinks he has lost his mind, Horton is determined to help.

Fox Animation's Blue Sky Studios is taking on animation tasks, a duty they have proved quite capable of after this year's hit Ice Age: The Meltdown, which reaped $650 million worldwide.