The phase related to that glass tube is a reference to another chapter later, after the end of the heartbreaking arc and before the Deviculum arc.
And that teacher was some kind of poacher. Which reminded me of that merchant who sold something illegal from the Kalego gaiden story manga series.
In any case, I think that Urara is not perverted as Leiji claims, but just feels useful to others like her older/younger sister Clara is.
I admit, considering that the academy is in an aquatic environment, I would like to see a magical beast with the appearance of the Loch Ness monster. Because I saw the monster named Kraken in that arc on the beach.