The way I see Mandelbrot ( Z <- Z*Z + C) is as an iteration using co-ordinates in the complex plane. Z is X+iY where X is the longitude and Y is the latitude. So the plane is a 2-dimensional map.
C is a constant throughout the calculations, so unless one changes the rules of Mandelbrot, it does not give another dimension.
A limit is set for the allowed values of Z, as new Z replaces the old. The count of iterations up to the limit has been used to define the colour (at the "designer's" discretion). It could also be seen to be the height.
I altered C between two images, simply to get a different perspective between the two - hoping to get the complex plane slightly tilted. My "squint" image of a plane is at
http://www.wehner.org/3d/towne/trapezia.gif . The further back you sit from the screen, the stronger the 3D illusion. You squint so that the left image is seen by the right eye and vice-versa. When you achieve stereopsis (the double-vision goes, and the image "clicks" into 3d), you see three images. The 3D one is in the middle.
I had not been aware of the abundance of fractal animations until I started exploring this forum. Some of those I looked at showed the "height" as an additional shift in the vertical (the Y axis). Here, the near overwrites the far. When this is animated as a sideways movement, hidden parts of the far image become revealed. This, again, is not 3D. It is changing perspective.
The correct facts about visual perception of 3D are those contained in Professor Charles Wheatstone's paper - which I retyped and put on my site.
However, the kinetic effects of changing perspective were not included in his paper. My "wobbly" Wheatstone is part of that story.
People are quite happy to go to the cinema, or watch television, where the images are 2D because there are enough depth-clues due to changing perspective, and also due to the vanishing point, for most purposes. However, 3D it is NOT. The word 3D has been constantly misapplied by people who really mean perspective.
3D should be a TOTAL simulation of what one sees in real life.
Another factor is peripheral vision (as in Cinerama) - but who can afford the computation-time to create wall-to-wall Mandelbrot?
Charles