Baby Melon is a humanoid watermelon shaped like Steven with two black watermelon seeds for eyes. Baby Melon is underdeveloped compared to the other humanoid melons resulting in him having several features that make him unique. He only comes up to Steven's chest when standing next to him, whereas the other humanoid melons are equal to or greater than Steven's height. Baby Melon's head is smooth while the others have curved bumps on top of their heads which resemble Steven's hair. He has lighter skin, than other fully developed melons, with no visible facial features.
Steven created Baby Melon through his newly discovered phytokinetic ability, inherited from his mother, Rose Quartz. The day before prior to Baby Melon's "birth", Steven engaged in watermelon seed spitting contest with his dad. He won the contest by performing his 'hurricane spin spit' maneuver which inadvertently scattered watermelon seeds all around the It's A Wash car wash.
Steven woke up the next day to discover that the humanoid watermelons over night and covered most of the area outside of the car wash. After retrieving The Crystal Gems for help, he took Baby Melon from Amethyst in fear of him getting hurt, since he's 'just a baby'. Since this moment, Steven showed a favoritism toward this particular melon and named it "Baby Melon".
Outside of Funland, Steven ended up giving away or selling the other Watermelon Stevens, except for Baby Melon who he wanted to keep for himself. However, Onion attempted to steal Baby Melon after being rebuked by Steven who told him, "Baby Melon was not for sale". During Steven pursuit of the fleeing Onion, Baby Melon is able to escape out of Onion's arms and run to Steven to hug him. Steven took Baby Melon with him after he realized the other Watermelon Stevens were probably alive as well.
Later, when all the other humanoid watermelons are attacking the Crystal Gems, Baby Melon sacrifices himself to stop the fighting by punching Steven in the stomach. This causes the other melons to jump on Baby Melon and attack him to protect Steven, 'killing' Baby Melon as a result.