[JakubTyl (OP)]

Are there any animals or so, who has growth of non-organic matter? For example animal that would live in rocky area and would have actual stones on its skin because of cover-up to not be eaten by predators? Or animal that would live on a tree and would have actual tree bark on its skin because of cover-up?
Or is it possible only to achieve that actual animal has skin made of for example shell and that shell looks exactly as stone by color and texture but it is not stone its shell?

[evan_au]

There are many examples of animals using camouflage to avoid predators, or to avoid being seen by potential prey.
- Octopus
- Insects, birds and snakes (slideshow)

There are some animals which attach small objects from their environment to themselves to make them harder to spot.
- Moth pupae
- Crab

And there are many animals which just hide under rocks, leaves or tree bark, so they can't be seen at all!

[CliffordK]

Barnacles grow on whale skin.  They aren't considered either beneficial, nor particularly harmful to their hosts.

Hermit Crabs pick up shells from other organisms to use as their own.

Chickens and many birds swallow rocks essentially to be used as teeth in their gizzards.

There is a Trumpet worm, and perhaps several similar species that create a hard tubular shell around themselves by binding sand into a tubular shell.  Also see the Sandcastle worm, and the sand tube worm, or ice cream cone worms.

[dlorde]

Calcium carbonate (chalk) is inorganic, but is secreted by many creatures to make shells, skeletons (e.g. coral), etc. Bones and teeth are made up mainly of hydroxyapatite which is inorganic, and the chiton mollusc has teeth made out of magnetite (an iron oxide), the hardest substance made by biological processes.