The bump texture on the shell surfaces is generated by Perlin noise in its mesh network. Based on that, points are randomly generated on the surface as the branches' roots.
Regarding the growth-generating logic, the first segment root of the branches extends along the surface's normal to grow as the initial generation. Following that, the endpoint of the root will be the recursion list for the next start point of the iteration. Points will find the closest points inside the designated Volume, compute the unitized vector, create a new line connected to the previous end, and follow the rule to generate the pattern. All generated points will be stored as a list in the recursion function.
After generating the growing process of the lines, create the surfaces with random radiuss' as organic branches.