I was inspired and took lessons from Inigo Quilez's article on FBMs, so I played with distorting the space in a way that at times it look as if you were doing traditional paper marbling. But now with some flexibility in changing colors and also rapidly increasing distortion, I was able to produce some interesting effects.
I just used Inigo Quilez's FBM technique with some simplex noise as you can see in this fragment shader code to produce a sort of curly effect in some of the circles of distortion.
The one above looks like many different cells together, all shifting about.
The code for the above just combined many simplex noise functions layered on to pof each other to create that effect.
Sea Blue and Bubblegum Pink Colors
I warped an image of sea waves, and then a picture of a pink marbled paper so that I could then sample those interesting colors and marble and distort them.
I used the code here to generate those two.
Studio LAB Logo Contour Line Marbling
I was inspired by some of the imagery I saw in the excellent 3Blue1Brown video on turbulence, and recreated it partly in the backgrounds of the Studio LAB logo. I started out with black/green colors, like the ones I saw in the video, and then experimented with different pairs of colors as I made variations using this code. It ended up looking like contour line topographic maps.