WIP
Update 4
Changed the purple into a ghostlier tone.
SilvanRaptor suggested on Discord to move the eyes from the white skull into the sides of the chest lid. I am not used to that look yet, so anyone please tell me whether this eye position or the previous one looks better.
Also I briefly flirted with the idea of having the tongue tip be spear-shaped and adding a spear-like tail tip for symmetry, but then decided to stick with the simple forked tongue. You can see the spear-version here: https://imgur.com/a/9rKj3
Update 4

Changed the purple into a ghostlier tone.
SilvanRaptor suggested on Discord to move the eyes from the white skull into the sides of the chest lid. I am not used to that look yet, so anyone please tell me whether this eye position or the previous one looks better.
Also I briefly flirted with the idea of having the tongue tip be spear-shaped and adding a spear-like tail tip for symmetry, but then decided to stick with the simple forked tongue. You can see the spear-version here: https://imgur.com/a/9rKj3