After a very long search, I finally got my hands yesterday on a depth black clack skull, but then I found out something that killed my excitement and I thought was worth sharing.
I've noticed that while my other MX skulls match perfectly in size, this skull was a bit smaller. Initially I thought that maybe earlier casts were different in size, but after asking around I realized that's not the case. Also, it has some minor, but noticeable imperfections that I didn't see in any of my other skulls. As its butt looks pretty legit, and some people might trust that alone to validate clacks authenticity, I thought it's worth raising awareness that such fakes exist as well. You can find out an album with some comparison pictures that I took here:
https://imgur.com/a/uKThX5I