Sweet chestnut

Chestnut fruits are inside the thorny capsules of the picture and they fall off during the automn. They are delicious to eat when roasted, boiled or even raw and nice desserts can be made from them such as marron glacé.
Until the introduction of the potato, it was one of the main sources of carbohydrates in north and western Spain.
Fresh chestnut fruits have about 180 calories per 100 grams of edible parts, which is much lower than walnuts, almonds, other nuts and dried fruit. Chestnuts, as with all plant foods, contain no cholesterol and contain very little fat, mostly unsaturated, and no gluten.
They are the only "nuts" that contain vitamin C