Non-Sentient Alien Life

[Draegon]

I've heard that true aliens will never be in the game, but I realized that limestone is formed from crushed sea shells and what not. But how would it form en masse without non human created life? I was thinking that basic alien life could be added, even if they're just very simple. The chances of no other life existing at all is REALLY small.

[ChromeMax]

You do realize that limestone deposits come from animals other than these "aliens" that you claim to have roamed the Rimworlds? It's extremely innacurate to predict that it was sentient life forms that existed on these Rimworlds.

[Boston]

I've heard that true aliens will never be in the game, but I realized that limestone is formed from crushed sea shells and what not. But how would it form en masse without non human created life? I was thinking that basic alien life could be added, even if they're just very simple. The chances of no other life existing at all is REALLY small.

How did outcroppings of limestone form in real life, then?  Humans didn't create it.

[carbon]

I think the OP meant non-Earth-based life. That was reasonably clear from context.

Also, why are we bumping a weeks old post just to mock it?

[DraconicGaming]

I've heard that true aliens will never be in the game, but I realized that limestone is formed from crushed sea shells and what not. But how would it form en masse without non human created life? I was thinking that basic alien life could be added, even if they're just very simple. The chances of no other life existing at all is REALLY small.

Funnily enough, I found some rather flavorful text while looking through the adult backstories using Prepare Carefully. One of the backstories, the Storyteller, hints at "ancients", since the person with the backstory says he wants to "grow scales to look more like the ancients". Perhaps that is the missing thing he is talking about...

[BetaSpectre]

We already have alien life, but having more of it would be cool too.

[nccvoyager]

Well, according to the fiction primer and the cryptosleep briefing, all (known) life currently on RimWorlds are genetically-modified from original Earth stock. (Even mechanoids are originated from humanity, being originally created as labourers, servants, and stuff.)
"Seed" ships were sometimes sent out that would attempt to create a habitable environment for any future colonies that may arrive, and many other RimWorlds are populated with the offspring of early colonists who attempted to terraform the worlds, and Earth-stock animals.

[Draegon]

I did mean non-earth based life btw. Also it doesn't seem like the primer mentions how long ago the seeding started although the game is set about 3500 years in our future, and as far as I know limestone takes quite a while to form. More than a few thousand years at least for the amount that exists in the game.

[nccvoyager]

Indeed, the limestone is a little weird...
However, a quick search brought me to this:
Geology [dot] com - Limestone

Some limestones can form by direct precipitation of calcium carbonate from marine or fresh water. Limestones formed this way are chemical sedimentary rocks. They are thought to be less abundant than biological limestones.

As such, non-biological limestone is entirely possible, though considered more rare on Earth.

Also (on the same page) found this:

Limestone can also form through evaporation.

In a cave, droplets of water seeping down from above enter the cave through fractures or other pore spaces in the cave ceiling. There they might evaporate before falling to the cave floor. When the water evaporates, any calcium carbonate that was dissolved in the water will be deposited on the cave ceiling.

The limestone that makes up these cave formations is known as "travertine" and is a chemical sedimentary rock. A rock known as "tufa" is a limestone formed by evaporation at a hot spring, lake shore, or other area.

Further down the page:

Travertine: A limestone that forms by evaporative precipitation, often in a cave, to produce formations such as stalactites, stalagmites, and flowstone.

Flowstone is defined as "rock deposited as a thin sheet by precipitation from flowing water."

It is notable, however, that limestone requires liquid water in order to form.
This means that in order for limestone to form on these worlds, liquid water needed to be on these planets before seed ships arrived.
That being said, however, in order for these planets to support human life, these planets would need to be within the "habitable region" of the stars they orbit, which would make the likelihood of liquid water much greater than it otherwise would be.

Therefore, it is entirely possible that limestone formed on these RimWorlds through natural chemical processes long before terraforming seed ships arrived.