"To discard the shells" means to get rid of or throw away the outer coverings or protective layers of something, usually in reference to shells of fruits, nuts, or eggs. Full definition
While there are some restaurant recycling programs for oyster shells, if you add in the other discarded shells from seafood that has been consumed — the mussels and scallops and clams, and even the cockles and whelks of the grotto — we're talking a lot of shells. (treehugger.com)
Coco bean mulch: Coco bean mulch is made from discarded shells of cocoa beans. (vetsaverspethospital.com)
A second study found that leaving empty pistachio shells on your desk after consumption reduces calorie intake by 18 percent compared to discarding the shells immediately.14 The shells, it seems, help to serve as a visual reminder of how much you've eaten, helping you become more mindful of your food intake. (articles.mercola.com)