Squigglers appear to be younger forms of Wigglers that first appear in the game New Super Mario Bros..
Squigglers, in this game, only appear in World 7-A as enemies. They can be easily defeated by simply stomping on them or defeating them with a fireball.
Only a single Squiggler appears in this game where, unlike the past game, is more friendly. It is seen managing a vegetable garden in Dimble Wood and it speaks with Bowser. However, Bowser says that vegetables are gross and meat is tasty, but the Squiggler only responds by saying a healthy body doesn't crave meat and hides behind a rock.