Jim Carrey will voice the title character in "Horton Hears A Who", 20th Century Fox's CGI animated adaptation of the Dr. Seuss book. His old "Bruce Almighty" co-star Steve Carell will voice the Mayor of Who-ville reports the trades.

"Horton" was scripted by Cinco Paul and Ken Daurio, whilst Jimmy Hayward and Steve Martino will direct. Carrey plays the elephant who hears a cry of help from a floating dust speck, and strives to protect it from neighbors who think he's nuts.

The film, which is being produced by "Ice Age" makers Blue Sky, will be released March 14th 2008 by Fox. Despite nabbing rights for the sequel "Horton Hatches an Egg", both Carrey and Carell are only signed for one film.