1560s, to remove (a nut, etc.) from a shell, from shell (n.). The meaning to bombard with shells is first attested 1856. To shell out disburse (1801) is a figurative use from the image of extracting nuts. Related: Shelled; shelling.
There are 14 calories in 1 cup, slices (3 oz) of Nopales (Cactus Leaf), raw. You'd need to walk 4 minutes to burn 14 calories. Visit CalorieKing to see calorie count and nutrient data for all portion sizes.
Although avocados have the highest fat and calorie content of any other fruit, they have a high nutritional value that makes it well worth it. In a single raw avocado, it can contain around 300 calories, 4 grams of protein, 17 grams of carbohydrates, 13 grams of fiber and 29 grams of total fat.