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.
The nopal, or prickly pear cactus, is among the plants native to the Sonora Desert, which is in Arizona and parts of California and New Mexico. You can eat cactus pears, or prickly pears, after removing their strong, sharp thorns.