Jane Street interview questions

All financial firm interviewers that came to our university are well-dressed professionals from Bulge Bracket firm names (Morgan Stanley, Goldman Sacchs, ...) to small boutique firms (Lazard, ...) EXCEPT for the Jane Street guys. I was interviewed by a nerdy looking person in a t-shirt and jeans (I have nothing against nerdy looking people. This is purely an observation). The guy either had little social skills in comparisons to interviewers from other firms, or was deeply uninterested in getting to know people and their resumes. He literally spent 3 minutes talking about my resume, and 25 minutes asking me math and probabilty questions, which was strange, but I guess fair too given the position that I was applying to. When he asked me what my favorite course was, I replied "Financial Institutions. It's a course where I got to learn about various financial institutions ranging all the way from commercial banks and insurance agencies to hedge funds, investment banks, and private equity firms". The interviewer then replied "Oh that sounds really cool. I know very little, if any, about these things, haha". I laughed along, but I would lie if I said that I wasn't put off by his comment. The interview then started with 25minutes of math and probablity.