Rock Formation, Daniel Castillo Calvo on ArtStation at https://www.artstation.com/artwork/0d3AY
Zbrush and Mudbox Sculpts : Great volumetric rocks. This texture pops out.
Zbrush rock sculpting technique: Build up large forms with ClayTubes. TrimSmoothBorder brush with square alpha to define the rock texture. Adding and subtracting with specific brushstrokes to grip onto the uneven clay tubes surface.