Wormy was a monarch caterpillar who was later turned into a monarch butterfly in the episode, "Wormy."
He was a light green caterpillar that has black eyes, and white spots.
He is orange, with black stripes and black on the outermost parts of his wings.
At some point, Sandy bought him in Texas. Sometime later, she took Wormy to her home in Bikini Bottom.
He later turned into a butterfly.
When SpongeBob and Patrick were pet sitting for Sandy, they played games such as hide-and-seek and tag. But over night, Wormy metamorphosised into a butterfly and scared everyone in Bikini Bottom because they've never seen a butterfly before.
His close up of him in his butterfly form was actually a closeup of a buzzing horsefly.