Someone on tumblr made the comment "silverfish are REAL?" on one of my posts and I didn't think much of it, but then one of my students said the same thing when I showed them a silverfish near one of the vents explaining what they are and why they were there.
That's when it hit me.
MINECRAFT
They think it's a made up creature from minecraft!
(Totally gonna tell them that endermites and shulkers are real too next time this happens. heh heh heh heh)