Sparkle (also known as Ricky) is a baby who appeared in "BMO Lost." BMO found him in the forest and at first thought he was a carnivore. Upon discovering that it was a baby instead, it thought Sparkle was lost. So it tried to take him home with it until his mother came along and took him instead.
He is a large baby wearing a white diaper and nothing else. His eyes are large and black, and he has no hair. Like his mother, his skin is salmon and the left hand is a flipper-like appendage. This flipper is used to create a distinctive call when pressed against the lips.
The pudginess and distinct pink skin of Sparkle look very similar to the giant ogre seen in "The Enchiridion!"
A baby similar to him appears in "The Prince Who Wanted Everything".
Sparkle is shown to have some understanding of his surroundings as he listened to BMO's instructions on two occasions and carried them out without protests. He was also the one who replaced BMO's batteries correctly back into the compartment after BMO had taken them out due to them being wet. Sparkle is incapable of speaking and instead gurgles, giggles, shrieks and huff-and-puffs to communicate.
And though he is capable of crawling, he didn't appear to mind being dragged hand and foot, by BMO, through the forest.