One of the favorite bits of terrain from the “DEAD” Kickstarter by Printable Scenery were the Burbling Pits because they seemed small and easy to print and also useful for both the odd bit of dungeon decor and wargaming difficult terrain. These two are not burbling, per se, but are rather then skull variation (there is also lava/slime and water/ice).
Close up, you can see the “topographical map” effect, which as far as I can tell is fairly unavoidable but thankfully isn’t that visible from a typical gaming distance. I’ll see how they paint up.
This little fellow is a free Arcane Plynth from Thingiverse. This is straight-up dungeon decor/scatter terrain and best of us was quick, easy, and cheap to print. Thanks Thingiverse!