lichens

Clover-like lichens are spreading down the three steps and have begun to take root on the stoop itself.

Thus its color is blue-green, as it can be seen in some lichens that have only symbiotic cyanobacteria.

The reason is that wild lichens grow very slowly and exploiting a species for a food supplement would cause a very high risk of extinction for that species.

Interestingly, lichens do this today: they are composite organisms of fungus and photosyth (algae or cyanobacteria).

It would be awkward if a contaminated probe brought lichens to Mars and it slowly turned blueish-green before our eyes.

I still expect them to do some kind of photosynthesis, just like lichens, and that would explain their height.

It's not specifically written in the article, perhaps because it's well-known, but the reason lichens are studied on gravestones is they have dates on.

In either case the first thing to do would be to seed it with engineered robust lichens, or the like, just to get things started.

If nothing is there, then we can move lichens etc without fear of contamination.

I've always thought that lichens were only found on hundreds- or thousands-of-years-old rock exposures.

I dream of artificial lichens on silicone wafers making sheets of graphene.

I feel the default should be something more like lichens.

What really excites modern biologists – and what the article completely fails to discuss (even to the point of claiming "this rule seems to govern all life") – are the numerous and dramatic exceptions to the rule: naked role rats, tardigrades, certain cnidarians ("immortal" jellyfish & hydra) and planarians, various lichens...

Lichens pretty much were what created the first terrestrial organic material.