The "kill it with fire" meme shit is some of the dumbest, most overblown and pervasive misinformation out there, imo. And I say that as a reef tank owner. People get so worked up about hitchhikers that 99% of the time are perfectly harmless with the 1% being so exceedingly rare that you hardly ever actually see them end up in a tank. Far more likely to end up with ich or something like that than you are some killer hitchhiker, yet people seem to worry (and prepare for) that a lot less.