A lot of comments are saying we could eat the urchins. Sure. But creating yet another mass food production from a single species is like what we did with cows - now we have an ecosystem with a single point of failure.
The only way to fix this is to have as complex and diverse a food web as possible. That way if one species goes down, like the way the sun starfish has, everything else doesn't collapse around it.
2,234 readers admitted to having used psychedelics. Of those, 285 (= 12.8%) stated that they had some hallucinations that persisted afterwards. 219 (9.8%) said they’d had them for a while and then they had gone away. 66 (= 3%) stated that they still had the hallucinations (one limit of the study: I don’t know how long it has been since those people took the psychedelics).
But most of these people reported very mild experiences; on a scale from 1-10, the median severity was 2. The most commonly reported changes were more “visual snow” (ie “static” in the visual field), slight haloes around objects, and visual trails. Many people reported that if they stared at a textured area like a carpet long enough, illusory geometric patterns would start to form. Only a few people noticed anything weirder than this.
So, 3% of a small study have relatively mild visual effects. Oh no!
via here: https://dfns.dyalog.com/c_life.htm
I figure that when we finally figure out the answer to the universe it will be something akin to this parsimoniousness.