Textured Spirals

Crackled Spiral 1

Crackled Spiral 2

Crackled Spiral 3

Crackled Spiral 4

Crackle is more commonly used to describe a sound but it can also be used to describe glazed pottery or glassware bearing a decorative surface network of fine cracks, and as you can see thats exactly what the variation called crackle does in Apophysis.
By changing the variables (size, power, distortion etc) of this variation you can get many different types of "cracked" looks, here just a few results i have been able to get on a simple spiral.