In the early days of the Muppets, the character Kermit was not a frog. He was introduced in 1955 on the show Sam and Friends with roundish feet instead of flippers and no collar. As Jim Henson described: "all the characters in those days were abstract"; Kermit was simply a lizard-like creature, and was not a specific species. Kermit truly became a frog in the late 1960s. However, the exact moment of the transformation has been unclear. Whereas most official sources list the 1971 TV special The Frog Prince, research shows it happened earlier.