Some information about uv mapping: Seams will have to be marked vertically on every symmetry division and possibly three times horizontally. Every bump would have a seam marked from the nearest division to it’s furthest edge + some more edges to unwarp better.
Symmetry center would have to be placed in the middle of a texture space (on vertical axis for 2 sided creatures, there is no center point for them). So the texture would be mirrored allowing symmetrical and asymmetrical coloration.
Different tissues could have different looping normal/ specular textures to make them look more smooth, dry, soft etc. Early multicel organisms would be translucent, similar to how cells look and possibly have bright dots on them just like on microorganisms we can observe in real life.