Death Mask and Skull

There is something about this stone which reminds me of a death mask. According to the article Screaming Mummies by Mark Rose, the phenomenon of the frozen-mask-of-agony is due to rigor mortis. Could this be what the artist was trying to capture in stone? From another angle, the face looks more like a skull. There are some other images as well, but the mask and skull are the dominant ones.