Osmeterium

Someone waved his osmeterium at me today, and it smelled just awful.

Before you start thinking Chris is a pervert with freaky anatomy, I should explain that an osmeterium is a fleshy, retractable organ above the heads of swallowtail caterpillars, which gives off a pungent odor when everted. I had only read about it until today, when I noticed that one of my black swallowtail cats was perched precariously on a half-broken branch of fennel, in danger of plummeting three or four feet to the ground (