In this thread post your most idiotic reefing mistake

[Magickiwi]

My biggest mistake wasn't really my mistake exactly. I simply listened to the dude at the LFS when he said a green brittle star was reef safe. Well by reef safe he meant it wouldn't eat corals, what I THOUGHT he meant was that it would co-exist without harming anything in my tank (Normally what is meant). Several fish later I finally caught the bastard in the act and then had to take apart large portions of my rock work to get the big sucker out.

Lesson learned: People at the LFS aren't necessarily speaking in the same context as you so do your own research and trust nothing unless you've verified it with a valued source.