Assume Cylindrical Sharks

Apparently someone in my social circle at college (possibly me) regaled everyone with a math or science question that began "Assume cylindrical sharks..."

I'd forgotten the incident, but it does sound very familiar now that someone has brought it up.  But I still don't remember the context at all.

So of course, I promptly googled "assume cylindrical sharks," and here was the first hit:

Kitefin Shark - Dalatias licha WHAT TO LOOK FOR
This is a medium-sized cylindrical shark with a short, blunt snout, and thick, fringed lips. Its spineless dorsal fins originate behind the pectoral fin rear tips, with the base closer to the pectoral than the pelvic fin bases; the second dorsal fin is larger. It has a weak ventral caudal fin lobe, and most of the posterior margins of its fins are translucent. 

So apparently cylindrical sharks are for real!  Who knew?  (Certainly not me --  I took physics, chemistry and engineering classes in college.  No biology.)