This is readily recocgnisable as an outlying part of the famous 2-D Mandelbrot Set. 'Dwell' is a mathematical term for the length of time the function z squared + C + New Z [where Z and C are complex numbers] can be riterated before it 'escapes' to infinity. All values for which the function does NOT escap[e to infinity are withing the set. Outside is a region in which the 'dwell' varies in a way which can be colour coded or 'rendered' according to the 'dwell' value. It isthe strytle of such rendewring which gives the Mandebrot Sety printouts their semi three dimensional appearance. It is the aesthetic taste of the individual artist in choosing this render that often determines whether the result is artistically 'interesting' or not.