Also known as "The Amazing Mouli", it's a small hand-drive food mill (hence the name) that reduces soft
fruit or any kind of cooked
vegetable (and some
meats, such as
chicken liver) to a puree -- in other words,
mush. Mushed fruits and veggies being useful as sauces, as a base for
souffles,
mousse,
sherbet, etc, as well as being tasty in themselves (mashed potatoes, anyone?), this tool (and a similarly rotary hand grater) used to be wildly promoted during the
60's, when its
French provenance gave it a taste of the
exotic.
Still useful in low-tech kitchens, or for people who want a really hands-on experience with food, it's mostly been superseded by the food processor.