Inchworm
This is a one-line variant of scroll art, where the \b backspace character is used to erase text on the current line. Snail Trail is another example of this. In Inchworm, a string of letter O's do a simple inchworm crawling animation until it reaches the right edge, at which point, another inchworm begins on the left edge. The speed and length of the worms are adjustable and randomly set for each worm in this animation.