Ok. But what does that mean in the context of the comment that you replied to? (Which doesn’t talk about decisions or nature chasing things, at least as it stands now.)

Is a harder shell which has higher costs than benefits selected out? Maybe we’re all repeating the same thing.

Ah I get what you’re saying. My point is that yes, some other type of shell probably selected out and this one wasn’t. Maybe it was dumb luck, maybe it was a slight advantage in a very specific condition that allowed it to persist, but ultimately we can only theorize.