Re:The head of the crayfish?
After reading Mike's post and not going any further, I guessed he was talking about something a whole lot bigger than our crawfish here. It takes something like 7 lbs. of boiled crawfish to get 1 lb. of tail meat from it. At crawfish boils, it's common to boil 50 lbs. of crawfish at a time. When eating them, the tail will get popped off first, and squeezed, people will suck the crawfish boil juice from it, and some people stick their pinkie's inside and get what they call "that good crawfish fat" but I never heard of eating anything from it other than what I mentioned. The heads and shells make a great stock.
It's dying out just because it's so labor intensive, but some folks used the crawfish heads for making bisque. The heads were cleaned out after a boil and most of the parts that are recognizable as part of the head are removed, so you basically have just a shell, which was used for a stuffing made of finely chopped onions, garlic, celery etc., seasoned bread crumbs, and chopped crawfish tail meat. These days some people will make "boulettes", where the same stuffing is formed into a ball, or torpedo-shape, and fried, then added to the bisque, as the heads once were.