Perhaps the reference can be worked in later. Some sort of noise heard in relation to it. As for the Worm, point. I think the design came before that dissipating detail came to light. There's a possibility that the Worm, when it grows large enough, is capable of actually hunting and eating other Grimm (which in turn hunt down even more things to feed to the Worm gestalt). It's just that gluttonous. I'll probably have to clarify the concept of the mud further, I suppose. I could argue that it's only the least decomposed corpses that still retain significant musculature and skeleton that are used, and the oldest stuff is what's been downgraded to mud. At any rate, such abilities can be removed in later revisions.