What is roller?

Does anybody know what is roller worms? I can not understand what is the “helically twist when moving” like.
Thank you!

A Rol or roller phenotype is perhaps one of the best and most obvious worm phenotypes (next to the dvelopmental defect we fondly call quasimodo).

Have a look at these short videos:

short nomarski clip

And in this one, after the camera pans, up, you’ll see a roller right in the middle of the screen.

Fluorescence with Roller

Thank you very much!