Question

Why the soap nuts have hard shell

Answer 1

Soap nuts are originally the berries which are soft. But they earned the name “nuts” because of the way that they dry into hard shells resembling nuts, as opposed to squishy fruit.

Answer 2

Soap Nuts are Soap Berries which contain natural soap which is called saponin. They grow on the Sapindus mukorossi or Soap Berry trees in the Himalayas. They are actually berries and not a nut. They grow on trees, ripen and drop to the ground. They are then collected and dried naturally in the sun so they have a hard shell.