A zipper used continuously arranged teeth to join or separate clothes, bags, and tents.
Snape, who came from the Muggle world, should have known that. Even if he did not, seeing students from the Muggle world wearing clothes with zippers should have told him how unnecessary that entire dense row of buttons on his robe was.
A normal men's coat only needed three buttons at most. Some only needed one. That way, there was no need to worry about fastening the wrong button.
Did he not find it troublesome to put on and take off clothes like that every day? If he fastened one button wrong, he had to start over.
Pomona glanced at the sky beyond the greenhouse. It had already grown dark.
She brushed the dirt from herself, removed her dragon-hide gloves, and called the students serving detention back to the castle for dinner.
Filch loved punishment and always made students who had made mistakes do meaningless repetitive work, such as polishing the trophies in the Trophy Room.
Pomona allowed them to pick ripe fruit from the trees. Some were keen on using their wands to clear away pests, treating them as targets for spell practice.
In short, they were not all that opposed to returning to the castle with Pomona. On the way, they ran into Hagrid. Ever since Buckbeak had injured Draco, Hagrid's classes had become terribly boring. Every year was taking care of Blast-Ended Skrewts.
He looked utterly dejected. Perhaps it was because, aside from the problems with his classes, Malfoy had sued him over Buckbeak.
Pomona therefore gave up on asking Hagrid what medicine should be used for Fluffy's bite.
Quite a few of the students serving detention were Gryffindors. They skipped and hopped along the way, without the slightest dejection at being punished.