Procedural Blender nodes material; highly customizable octopus skin with granular color-change. Works with Eevee and Cycles.
This material is structured as closely as possible to real octopus skin. Pigmented cells in an octopus' skin, called chromatophores, expand and contract in order to reveal various colors at the surface of the skin. This material replicates that action in the node group Chromatophores, which controls the overall color-change effect by enlarging small dots on the surface of the material.
The larger patterns are controlled in the Cells groups (labeled Cells: Small and Cells: Large). Try altering the scale and other settings in these groups to get different looks! The bump and displacement effects follow the same patterns.
The material comes pre-set to the colors in the preview animation. All the other colors and shapes in the preview images are made using simple tweaks to this node setup.