Part of the case study series.
About worldbuilding? Yes, because I had already provided the hypothetical world - the purpose of the question was to use the basis of that world to weaponize something for the entire hypothetical world to use.
Risking off-topic? Possibly risking Idea Generation, but I think enough restrictions were provided in the question to allow for a objective view on best answer.
About worldbuilding? Yes - this question could be referenced for future creature design of anyone who wants to have a world of creatures with 2 brains.
Risking off-topic? Again, possibly Idea Generation, but I think that enough restriction was given on the definition of "2 brains".
About worldbuilding? Same theory as the two brains question, so yes.
Risking off-topic? Nope. This one definitely has more than enough detail keeping it away from "Too Broad", and the details and pictures depict exactly what I'm saying/mean, so even Idea Generation is limited severely by the requirement to fit the provided pictures + description.
About worldbuilding? Yes, as it applies to any world that could use a projectile water weapon, which happens to be almost any hypothetical world with water.
Risking off-topic? Restrictions provided stop it from being too broad/idea generation, so no.
About worldbuilding? Yes, for essentially the same reason as the above 2 creature design questions.
Risking off-topic? Maybe too broad/opinion based. I probably didn't provide enough restrictions for this one. Luckily, since the majority of the answers were "not possible" answers, it was easy for me to pick the one answer that did actually answer the question properly.