This diagram plots every irreducible fraction between 0 and 1 as points, where a point's x coordinate is the fraction's value (from 0 to 1) and its y coordinate is the fraction's denominator (from 2 to whatever the maximum is).
It makes really nice patterns the further the denominators go and I'd really like to know more about it. I think I remember finding it on Wikipedia or something a long time ago with a name along the lines of "the stars of x" or "the towers of y".
Maybe it's just nothing, though.
This is the graph of the reciprocal of Thomae's function.
https://en.wikipedia.org/wiki/Thomae's_function