Squiggler

A Squiggler is a miniature Wiggler that appears in New Super Mario Bros.

With three body segments and a head about twice the size as the other segments, this tiny Wiggler crawls around the perimeter of pipes. Squigglers are only seen in Level 7-A and are obviously the baby versions of the Wigglers. It can be inferred that they are born in pipes. When they mature enough they (presumably) become a Wiggler, then a Wiggler Fly.

Trivia
If Mario or Luigi jumps on a Squiggler, he will get no points. However, if one of the brothers Ground Pound on it, points will be earned.