My offering to the [Anatomically Correct Series][0].

I came across a curious creature, the [Hatch][1]!

> The Hatch is an adaptable creature whose wide-ranging diet allows it
> to integrate easily into most ecosystems. The Hatch has no eyes and is
> completely blind, although a photosensitive patch atop its head is
> capable of detecting even minor changes in overhead light, making it
> prefer dark caves and tunnels.

//Pictures edited out for now, as I'm not sure they are allowed.

**The Hatch's life cycle:**

Hatch Egg Hatchling Adult Hatch

**It's variants, based on its diet:**

Sage Hatch (wider range of organic food):

Sage Hatch

Stone Hatch (wider range of minerals):

Stone Hatch

Smooth Hatch (metals):

Smooth Hatch

**The main issues are some of its features:**

 - It can sustain itself on a strictly mineral diet, though it can eat
   organic food too
 - **It poops out coal!**
 - A single creature, depending on its diet, lays different eggs, which
   hatches its variants. The variants can lay eggs, which hatches the
   "normal" Hatch.
 - The last one, the Smooth Hatch, eat raw metal ores and poops out
   refined metal

These features are also the question. Can a biochemistry enabling this creature exist? Can the variants exist and "born" from a single creature?

**BONUS:**

(This can be skipped, if can't be answered)

 1. Could the Hatch evolve naturally?
 2. Could the Smooth Hatch exist? (Supposedly it can refine iron,
    copper, gold and even tungsten - so to me this feels the most
    unnatural)

 [0]:https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798
 [1]:https://oxygennotincluded.gamepedia.com/Hatch