Looks like a voronoi pattern. First thing that comes to my mind is that you can:
1- Create a subdivided plane and distort it with proportional editing etc.
2- Inset faces and delete
3- Use solidify and subdivision surface modifiers
4- Create a cluster of that plane with different levels (Problem is that geometry (planes) will intersect each other)
Here is a render:
Breakdown of steps:
Here is the file: voronoi_object.blend (855.3 KB)