Squiggler

A Squiggler is a miniature, likely quite young type of Wiggler that first appears in New Super Mario Bros. Unlike normal-sized Wigglers, Squigglers have three body segments and a head about twice the size as the other segments that has a sprout on top.

New Super Mario Bros.
In New Super Mario Bros, Squigglers can only be found in World 7-A; many can be seen crawling around the perimeter of pipes in the underground pipe maze area. Unlike regular Wigglers, they can be defeated, either by stomping on them, by throwing fireballs at them as Fire Mario, or by other methods. In this game, Squigglers are cream-colored.

Mario & Luigi: Bowser's Inside Story / Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey
A single Squiggler appears in Mario & Luigi: Bowser's Inside Story in Dimble Wood. This Squiggler manages the Wiggler family farm. Bowser meets with it and the Squiggler seems friendly. Bowser, however, states bluntly that vegetables are gross and that meat is better. The Squiggler reacts to this by saying that a healthy body does not crave meat and then hides behind a rock. It can last be seen during the sliding punch tutorial, where it can be found if the player tries to head south. Upon doing this, it asks Bowser if he can smash the rocks blocking the shortcut out of the farm. In this game, Squigglers are mainly colored yellow instead of pale cream.

The Squiggler reappears in Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey in the Bowser Jr.'s Journey mode, where it welcomes Bowser Jr. and Wendy to the Wiggler family farm.