Are they edible? Hmmm yeah! But be ready to meet one of the most sour fruits under the sun. The baby ones are tolerable, the medium ones will need some salt to dip them in. As for the mature ones? They are used as sour mix for meat/fish stew, can be made into vinegar, can be applied to remove unremovable stains (be ready for some discolorations on your clothes) and lastly, they can clean stubborn dirt on your nails. Just let your nails scratched the fruit deeply and be amazed. They are called KAMIAS.
Photos taken with my Samsung Galaxy S7.