White Child - 白子

Tonight we ate dinner at a local fish restaurant. We played the usual game of Russian roulette with the menu, choosing things at semi-random relying on educated guessing. One of our choices was "shirako" tempura, the kanji for which (白子) represented "white child" - which seemed to us likely to be a small white fish. Fair enough. It arrived, and instead it looked more like this:It was sort of squishy and wet inside. We persevered, getting through most of it, wondering where we'd gone wrong. Brains? Intestines? After the meal, we came home and looked it up in our trusty Japanese food glossary (which of course we didn't have on us in the restaurant). It says: "The sperm-filled reproductive gland of male fish". That's right. Eww.