I think there should be a caterpillar mob who eats long grass a flowers and saplings and reeds, I also think you should be able to tame it with cactus green and use him like a guinea pig, but when he gets to level 10 it can (if you want) turn into a cocoon and in 5 minecraft days a butterfly which you can fly on, but if you fly on it for 1 minute flat it will land, even if lava is underneath it.

sounds nice, but not every creep should be a pet! minecraft needs more challenge!