“Mister Froggy started, as most of my ideas do, with a few simple sketches (Fig.01). At first Froggy wasn’t a frog; I don’t know exactly what he was. Some sort of bug, perhaps. These sketches were very little; they were sort of thumbnails that I did very quickly, just to put the rough ideas from my head on paper.”
http://www.3dtotal.com/team/Tutorials_3/makingof_mr_froggy/mr_froggy_01.php