Oh that's some nightmare fuel all right: https://en.m.wikipedia.org/wiki/Japanese_spider_crab#/media/...

You should play Obra Dinn.

Long legs can't save it from Japanese cooking shows http://ironcheffans.com/?p=1573

Hey it's the "silence, brand" crab!

If the habitat was the bottleneck, we could learn about a convergence point that tells us about possible non-Earth life.

"Whatever the advantages are, they do not apply in all habitats because some groups have also lost carcinization; one modern example being the frog crab."

Fun fact: life has terraformed the Earth (pun fully intended) into what it is today:

- Photosynthesis created and maintains the current composition of the athmosphere. By removing too much CO2, it likely also contributed to several ice ages.

- Early life sequestered almost all the iron in the primordial Earth's sea into sediments, which turned into iron ores.

- We take the presence of such a basic thing as soil for almost granted, yet soil is created and maintained by life itself. At the same time, soil is only absent in environments where only extremophiles can survive. From this follows that it must have taken a lot of time for life to conquer the land and make it hospitable by creating a soil covering.

From these things, I (perhaps hastily) conclude that planets with life could actually look a lot like Earth. Or they can at least be recognized by the presence of chemically and physically unlikely features such as reactive elements like oxygen in their athmospheres.

Something farmers who are now inherently dependent on synthetics forgot is that plants can form soil on their own. Plants use deep root systems and can send up to half their glucose into the soil to build up organic matter in the soil. Bacteria and fungi digest the glucose and create small pores in clay soil which lets water infiltrate instead of washing nutrients away at the top. Droughts are rarely the result of a lack of water, they are the result of poor water retention.

The point is that plants are capable of terraforming the planet on their own. It isn't even a slow process if humans help the plants do their job.

That's fascinating. Do you happen to have a link to a study describing how deep root systems can transfer up to half their glucose in the soil?

I agree, but the first peak of atmospheric oxygen was more deadly than your description https://en.wikipedia.org/wiki/Great_Oxidation_Event

Maybe there are also path-dependent constraints. We shouldn't assume Earth life has tried every existing possibility so far. Or that we would know about every path taken.