This model is part of the growing "Gridfinity Anatomy" series. You can explore the complete collection here: https://makerworld.com/de/collections/10042958-gridfinity-anatomy 

Important: To view all models in the series, you must enable "Show NSFW" content in your account settings. This is necessary because some anatomically correct models are flagged as sensitive content by the platform.

How to enable: Account Settings > Settings > Show NSFW (at the bottom)

This skull is set on a 2x3 gridfinity base.

It is a remix of Skull by LD3d_lab - MakerWorld