I'm not a squeamish person when it comes to food, but balut - fertilised duck egg - did give me pause.
The embryos can range from very small, without any discernible "ducky" features, to being just days from hatching, complete with beak and down.
While fertilised duck eggs are most often associated with Filipino cuisine, the first ones I ever ate were cooked for me by a Vietnamese friend. She handed me one, still warm, with some salt and a smile that looked like a challenge. I couldn't let my reputation for being adventurous slip, so on her instructions, I cracked it and removed some of the shell - to reveal an almost fully developed duck embryo that looked absolutely disgusting.
I sprinkled it with a little salt, averted my eyes and took a sip of the liquid inside. It was the purest, most intense broth I've tasted. The solid duck portions were challenging but still delicious, because the meat was tender and the bones had a soft crunch. Oddly enough, the parts I disliked were the too-firm yolk and white.
Sadly, balut is unlikely to become a popular street-side snack in countries other than the Philippines and Vietnam - even though it is said to be good for male virility.