A factal is a closed shape with an infinite perimeter. This means that it has a finite area. Due to their infinite nature, fractiles generally need either a recursive or infinitely precise method of definiton. The two most popular fractiles are likely Serpinski’s Triangle and the Mandelbrot fractile.
Sierpinski’s Triangle
Open in DesmosMandelbrot Example: https://mandelbrot.site
It can be quite intruiging to play around and zoom in on these, especially the mandelbrot set.