I love entries like this that take the title in a different direction to what was probably the "intended" interpretation, but execute it well enough that it feels like the title was made bespoke for this particular module. Are we the crypt crawlers, exploring the crypts of Mictlan? Of course not! We are EXPLORING inside the crypt crawlers, who work for Mictlan. Of course!
The descriptions are really well done - the NPCs in particular are presented with slightly more prose than the rooms, but it works - nothing is wasted, everything is very readable. The actual dungeon layout is also very good. You had me at "left anus" and "right anus", which I'm sure is limacologically accurate anatomy, but they're also really well placed dungeon exits (and, perhaps, entrances...) relative to the rest of the layout.
Also that's a really really nice green.