WOLF'S EYE
I had a chuckle at myself not too long ago.  I use a lot of herbs and crystals in my soaps & spell works, so when I hear an unusal name. I think nothing of it.  Names like horse chestnut, deers tounge, tiger eye. 
And then there was the time that some one sudgested that I use Wolf's eye for a particular spell I was working on.  It was wrapped in cotton, sealed in a plastic bag.
Sure, I was game. I just thought it was a very fragile stone or herb.
Boy was I wrong!
I cast my circle and began working the spell, I got to the part where I needed the wolf's eye. I opened the bag, unwrapped the cotton and to my horror, it was not an actual eye, but an eye socket.  Complete with a little hair left around it.
I did my best not to scream. I'm not a squimish person by any means, but this shit just freaked me out.  I couldn't stop washing my hands after that ritual. Ugh!