I wanted to see if I could make a springo pumpkin & then decided to add a skull for variety. This model is made for a layer height of 0.2mm. LH is set at 0.3mm to create the defects. It does require using a knife to free up the layers afterwards.
One skull model comes from https://www.thingiverse.com/thing:906562. I forgot where I found the other more realistic one. I came across a Bash script made by vovcacik [https://gist.github.com/vovcacik] which can convert a 3d OFF model into an array for OpenSCAD's polyhedron module. I modified this slightly.
[Edit] I have added a smaller model which is easier to scale - pumpkin_skull.small.08.scad/stl.
The author hasn't provided the model origin yet.