Sometimes, there is interesting insight in exams of students. From the second midterm exam, a citation of a student paper:

"This has 3 roots but two are imaginary and there is no cube formula currently known to man."

as well as a grader pointing out:

"there is a cubic formula (and quartic), but no quintic".

Indeed this one of the most fascinating stories in algebra.

And here is an other nice quote which explains thy the surface area is zero: it is a wormhole.