This is a follow up question to my previous question: Rock/Mineral Ore Eating Organism

So these things: https://en.wikipedia.org/wiki/Lithoredo

They eat limestone. So I thought, what is limestone rich in? Calcite/Calcium. Perhaps a similar, more alien species of boneless mollusks could synthesize the minerals from limestone and also phosphorite for phosphate and grow bones, an entire skeleton even and evolve into humanoids.

Is this too far fetched or is this kind of biosynthesis reasonable within the realms of science fiction?

Edit: forgot to factor in collagen, but:

The major elements present in the mollusc tissues were sodium, potassium, magnesium, calcium, iron and zinc. Collagen was found to be the major protein in edible molluscs, and aspartic acid, glutamic acid, glycine, alanine and leucine were found to be the dominant amino acids.

Edit: changed "sandstone" to "limestone", my mistake!

  • $\begingroup$ That's what life on Earth did. What is ATP? $\endgroup$ Dec 3, 2019 at 12:20
  • $\begingroup$ That linked article doesn't actually say those worms eat sandstone. It says they grind sandstone with their teeth, but excrete it undigested. $\endgroup$
    – Archerj
    Dec 3, 2019 at 13:26
  • $\begingroup$ i read this as "orgasm that consumes minerals and synthesizes it into their bodies" omfg sorry $\endgroup$ Dec 3, 2019 at 15:04
  • $\begingroup$ en.wikipedia.org/wiki/Halophile there are salt eating microbes i also suggest looking at en.wikipedia.org/wiki/Extremophile extremophiles. i believe i heard that some bacteria or whatever eat iron. $\endgroup$ Dec 3, 2019 at 15:07
  • $\begingroup$ I think "sandstone" is a typo. These worms dig into / eat limestone. That is what has the calcium. Sandstone is silica sand. $\endgroup$
    – Willk
    Dec 3, 2019 at 15:11

2 Answers 2


Certainly. Lichens can grow on stone, and will generate acid in order to slowly metabolize it, so it's fully plausible that other organisms could metabolize it as well, if it contains useful elements. Furthermore, it's common for animals to eat pure salt if they can find any.


If these creatures live in the sea then sea water could provide many minerals and still more could be absorbed from trace minerals in the sandstone, although sandstone itself would provide no nutrition as it is composed of compacted silica. It contains virtually no calcium unlike limestone.

If the creatures live on land they will need more than sandstone (or limestone) to eat unless they are very simple like lichen. More advanced creature would need more than rock and air.

It should be noted that "synthesis" is usually used to describe organic chemical reactions, minerals cannot be synthesised from other minerals unless all of the elements required in the target material are present (or available elsewhere) in the source materials. You can’t make salcium carbonate from Silicon dioxide etc.

  • $\begingroup$ I meant limestone, my mistake $\endgroup$ Dec 3, 2019 at 22:26

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